Today I want make a card like tableview app, I find out that when you edit cell prototype in Interface builder, after you switch to other interface, contents in cell prototype will miss…
So I only can init the cell with codes…
Today I want make a card like tableview app, I find out that when you edit cell prototype in Interface builder, after you switch to other interface, contents in cell prototype will miss…
So I only can init the cell with codes…
Somebody ask this question at quora, this is my answer:
This is my answer of a quora question:
This is my answer to a quora question.
At China, a lot of developers and company say, they like use the strategy of Android first. Because there are a more larger user base on Android, and because the serious pirate problem you can’t easy get pay from user directly, so get more user base is always more important.
Someone ask this question at Quora, this is my answer:
|GNUstep||Cocoa (all)||simulate Mac UI||Linux/Windows/Mac||Yes|
|Cocotron||Cocoa (all)||simulate Mac UI||Windows||Yes|
|Chameleon||UIKit (all)||simulate iOS UI||Mac||Yes|
|Apportable||OpenGL ES / Cocoa touch(very little)||game development||Android||No|
|StellaSDK||OpenGL ES / Cocoa touch(very little)||game development||Android||No|
I am collecting all cross-platform mobile development tools to do some research, I will test them all and write down some of my impression of them.
Since 2007, after Steve Jobs announced the first generation of iPhone, iPhone immediately got a lot of fans, they love this product as crazy. But the big boys in the cellphone industry never think it a big deal. Nokia mocked Apple, No one will use a phone like that. Fans of blackberry looked iPhone user as freak, why on earth did anyone will use a phone without keyboard, how did you input? Yes, at the time of iPhone first generation, if you compared the function list of iPhone and a Nokia phone, you might say, this is a garbage, even can’t support 3G, etc. The New York Times and the Wall street Journal, they really liked this product and put a lot of good word for it, but they didn’t really think it will have a great future.
But after serval years, two giants (Moto and Nokia) in this industry have beed acquired by others, now people don’t like DC and DV anymore. One product of one American company, pulled down Nokia from its throne, made all the market accumulation of Japan digital products to nothing, all in one night.
But at that moment, iPhone didn’t support third-party apps yet. Now, some people are accusing Apple don’t support Web developers, they just don’t remember at that moment, iPhone didn’t support any native app, all the third-party apps must developed with HTML.
In this article we will talk about the history of iOS 1-8 SDK, and how these SDK change the developer and change the world.
iPhone OS 1 SDK announced at March 2008, Developers already couldn’t wait any longer, they rushed into, this was the beginning of the mobile internet’s golden age.
The first big update of iOS is iPhone OS 3. In this version, apple bought in a lot of functions, which users looked forward a long time, include copy and paste, landscape orientation keyboard, multimedia SMS, and so on.
For the developers, the significant point is, iPhone OS 3.0 SDK provided the support of iPhone accessories, and after that countless iPhone accessories appeared on the market.
And in this version, Apple started to provide Map API, and this brought out a new type of app, LBS App.
And music library access, people waited it long enough.
In this version, Apple started to provide a push notification service, use this service, all the notifications send from Apple’s server, iPhone only need to maintain one persistent connection with the server, then can get all notifications to any apps in the iPhone. This method can get best efficiency of power usage and performance. Since then, real online chat tools appeared in iOS platform, and this brought a great nightmare to all patients with obsessive-compulsive disorder, they started to busy on clear the number appeared on the right-top corner of every app icon.
In-App Purchase gave developers a new business model, they can make some free apps and games, and in the app they sale digital contents, chargeable functions and game props to make money. This function has great impact for App Store and whole mobile develop environment.
From the language point of view, after iPhone OS 3.0 released, developers usage rate of Objective-C raised from 0.1% to 9%, for now. On the Programming Community index, Objective-C already got the top 3 position. And it is wroth to mention that, Objective-C always isn’t a multi-platform language, is mainly used for iOS and Mac platform. Almost all the other languages at the top positions can use at almost all the platforms.
Figure 1: TIOBE Index for Objective-C
One big improve of iPhone OS SDK 3.0 is iPhone OS SDK 3.2 for iPad. In this version, Apple announced a new concept Universal App. Developers can provide both iPad and iPhone version in one app, the technic behind this is Fat Binary, you can put serval CPUs binary in one executable file. This technic has been used at Mac OS X migrated from PowerPC CPU to Intel CPU, and the migration of 32-bit to 64-bit CPU. The benefit of using this technic is that, user never need understand the different of iPhone and iPad, or PowerPC and Intel, or 32-bit and 64-bit, user can just download one app, and consider everything is done.
For help developers migrate app from iPhone to iPad, Apple support every iPhone app run at iPad, as 1X display model and 2X display model, Apple and developers may think that will make users happy. But very soon after iPad released, all the popular iPhone app can run at iPad, the developers were forced by users to provide a iPad optimised version.
Because iPhone SDK can run both on iPhone, iPod touch and iPad, so cause some ambiguity. Apple try to unify the brand, so from iOS 4.0, they change iPhone OS SDK’s name to iOS SDK.
Even from the first version of iOS, it is a fully functional UNIX base mutiltask operation system, but third-party app isn’t allowed run in background, any third-party app once it has been switched to the background will be killed. So some users and developers think iPhone is a single task system. But after iOS 4, Apple started to support all apps to quick switch, it means, after third-party app been switch out to background, it will not be killed, it will be suspended, once it been switch back, it will continue run immediately.
And for audio play app, VoIP app, LBS App, iOS 4 started to provide fully background running support. These consideration come from power supply, perform cace, functionality, may be can not fit all the needs of developers, but great improve the app catalog of App Store and their functions.
And this version, Apple started to use iAd, but for now, iAd still isn’t a very big deal for Apple.
The device announced with iOS 4 is iPhone 4, it is the first device support retina screen ever. In iOS 4 SDK, Apple provide a technic 2x image to support retina screen. Many developers don’t take seriously about retina screen, but very soon after that, eyes of users have evolved, they can easy tell if the app provide retina screen optimise or not, if not, they will keep complaining to the developers. So, just after three month or longer, retina screen optimise became the normal situation for App Store, all the popular apps have retina screen optimised.
From this version, Apple announced iCloud, this action means MobileMe is a total failure. iCloud has been mixed reception from birth, recently naked celebrity pictures leak event got iCloud more and more criticism. But you can’t argue, iCloud brought a lot of users to the Cloud Age. iCloud might still have some problems, but developers originally need buy their own servers, pay money to data storage, now they can use iCloud free to provide same function. And you know why, Chinese developers don’t very care iCloud.
At language level, iOS 5 SDK add ARC. Objective-C on iOS use reference counting technic to manage memory. Good side is this will great reduce memory consume and improve performance. But bad side is obvious, it need developers always watch memory, write code very carefully to make sure not leak (forget release) and not crash (early release or over release).
This causes a lot of pain and works to developers. ARC technic use LLVM to make static code analysis, automate add reference counting code, reduce a lot of works and difficulty. Then, it still harder than GC, but get the same performance with Manual memory management, and it have great performance and memory consume benefit compares with GC. So, it a petty good tradeoff of convenient and performance. Now, unless you are considering to support devices under iOS 5, all the project is using ARC.
Like iCloud, Storyboard’s release is mixed reception too. But in my point view, this improvement is great, but not prepared enough.
Storyboard transform entire UI interactions switching processes in the form of a flow chart to modeling, use it right, you will find that the structure of the entire project becomes clearer, and using Storyboard in Universal App you will find it is very convenient.
However, the file format issue of Storyboard (all views information in one file) make code management tool difficult to use in large projects, specifically when you need synchronise or merge. Also, because the transition from XIB to Storyboard too fast, Storyboard can’t perfect support some features of XIB yet. These issues will undoubtedly affect a lot of projects, so that they don’t want to use Storyboard yet.
Storyboard looks like a prototype programming tool
In addition, this generation iOS API also launched a very promising magazine rack – Newsstand, but the digital magazine industry as a whole decline, Newsstand did not ultimately form a big trend.
iOS 6, many specific improvements, but not many new things added. The first is switch from Google Maps Maps API to Apple Maps API. Apple’s map still subject to a lot of criticism, because there are some error and inconvenient, innovations and improvements of Apple were ignored by users. However, it seems that Apple is sure to provide your own map service. So developers can continue to use the official maps API or use Google Maps API. In China the problem is more complex, developers also can choose Baidu maps and AMap.
PassBook could have been the highlight of iOS 6, but unfortunately it has a good start, but slowly flow back to dull, Pass Kit users are not so many now. This strategy largely failed.
Overall, iOS 6 made a lot of detail improvements, and the entire system has become more mature, more stable and fit the user habits. This forms two voices, one is that iOS don’t need big change, change will cause chaos; another voice is iOS developing so many years, there is no changes and innovations, need big change.
Apple chose to change, the entire interface redesigned, UI and UE of this generation is the most controversial. “Apple boom-bust” This old-fashioned view after iOS 7 release also put it up. Countless people from all aspects of argumentation appearance, they think iOS 7 will fail. However, after released iOS 7, the officially results is, users’ upgrade enthusiasm are higher than any previous version.
Many application developers have caught the new operating system benefit, timely introduced new version, some even introduced re-pay new version, got a lot money.
From this generation, iOS applications began to support 64-bit, but for developers, it is completely transparent, most developers do not even need to do any settings to make their application support 64-bit.
In addition, Apple also launched its own 2D game engine Sprite Kit, but since most games have cross-platform strategy, so the Sprite Kit isn’t very popular.
In outsiders’ eyes, iOS 8 SDK is the most bland, because the appearance is almost identical with iOS 7. However, iOS 8 SDK is the largest iOS upgrade in developers’ mind. In this version, Apple for the first time allow communication between Apps in the form of App extensions; supported App extension types include sharing, action, today, photo editing, storage, and third-party keyboard. Among them, action, today and third-party keyboards are most attention.
Many operations, previously limited to iOS iOS platform security mechanism, can not perform elegantly, finally you can do it now.
For example, 1Password, an app widely used by iOS / Mac users, it can be very convenient to use in the Mac, when you use the browser to open a website, you just click on the 1Password browser plug-ins, it can be based on your current browser Web site address should be filled in, automatically match the user name and password. In iOS 8 Previously, users must open a separate 1Password, search needed Web site, and then copy the password, and then back to the browser or a specific application to paste the password, very inconvenient. And in iOS 8, 1Password extension made a motion to elegant solution to this problem.
Third-party keyboard after iOS 8 officially released in China, but also set off a wave of small boom, domestic manufacturers have done IME own third-party keyboard. There are many users see after iOS 8 support third-party keyboards, have said: This is n’t any reason left to use Android and jailbreak.
And from this generation, iOS began supporting Touch ID, Touch ID is Apple’s unique fingerprint authentication technology. Application using Touch ID, you can use a fingerprint to cache passwords after the user enter the correct password, when app requires again password, the user simply gently put finger on the Home button, can be very convenient and very safe. Because the fingerprint information is stored on a dedicated chip, operating system and applications can’t access the fingerprint information itself, can only be obtained if the fingerprint verification is successful.
The fingerprint cached passwords or other information on each machine can be clear, when phone restart, or fingerprint information modified, or just timeout, to fully guarantee safety. Another benefit of this design is that any application using a password, you can easily add fingerprint protection, without the need to modify the design of the entire application logic and use processes.
Health Kit is another major improvement of iOS 8, in fact iPhone 5s start using M7 processor, it don’t consuming CPU to tracking steps and almost don’t cost any energy.
Some people think this is a serious and qualified monopolies very complex market. But I happen to believe that enter the health care market is difficult, and is not necessary, but the health monitoring market in fact is empty, Apple is very easy to enter. Moreover, Apple’s main business is not making health monitoring products, but to provide integrate interface and operator interface. Soon after iOS 8 was released, we found step tracking software started communicate between each other. So you can imagine the future, one day you use X’s blood glucose meter, because their measurement is the most accurate, but you use the Y’s blood glucose monitoring software because their analysis is most intuitive.
Future health field is definitely not so simple as electronic medical, but as we can finally signs on the human body for more continuous, ongoing monitoring, we will be expected to develop exercises, treatment and care programs, based on each person’s symptoms, which far-reaching significance for the future of humanity.
We can see the Apple Watch can monitor and record heart rate data, step data at same time, in this case, the user can perform a long continuous multi-parameter measurements. Then one day you will find that you do not need the guidance of a doctor or health according to the guidelines for exercise and rest, because the system can be based on extensive analysis of your physical features, including the relationship between the frequency of heartbeat between exercise intensity and so on.
While released iOS 8, Apple also released a new programming language Swift, compared to Objective-C, Swift more object-oriented, removed all the burden of the C language, but keep on Objective-C compatibility.
In the API level didn’t modify any call of Cocoa touch, which greatly protects the time and energy costs on the old programmers Objective-C and Cocoa touch framework. Meanwhile, Swift is an innovative design language, is relatively easy to get started, a lot of people because Swift has sparked enthusiasm for iOS development. The language learned a lot from current popular languages. Write code in Swift is easy and convenient. But in order to ensure the safety of memory read and write, Swift proposed a new type of variable “Optional”, this has brought some benefits, such as tedious codes use Swift and Optional can become clear and understandable. But Optional also brought a lot of highly complex and ugly code. Because, Swift has, after all, a new language, and we hope that it will soon mature to give us the ease and convenience.
Another major improvement of iOS 8 is HomeKit. Use iOS device control smart home devices. This interface supports you use Siri to control home appliances, Harry Potter’s world is about to come in your home.
Another interesting API is Handoff, if you have the same application installed on the Mac, iPhone, iPad or using some same system apps, you switch from one device to another device seamlessly.
For instance, your are reading an article use Safari browser on Mac, suddenly you feel a little tired, want to play with the phone lying in bed, then you leave the table, lying in bed, turn on the iPhone screen, you will find an addition Safari icon at lower-left corner of the screen. If you pull this icon to unlock, iPhone will open Safari, then load the link you’re watching on your Mac before. Or, you’re writing a text message on the phone, suddenly felt the phone typing too slow, you can go open the Mac, hold down the Command key and the tab key to switch applications, you will find a list of application icons appear, and a short message icon in front of them, switch to this icon will open the system message application then automatically jump to dialogue before, resume the text that you have already typed. Not only that, Handoff technology also supports you use Mac, iPad to answer iPhone calls, outgoing calls using the iPhone as a router.
Although iOS 8 has just released, its inherent power has not completely been released, but people already are excited. Looking back five years, I think the iOS system has been improved in the forward direction, good rhythm. I hope we can develop more good app for this excellent system.
I am working on a mac open source project Wall-E, this project’s purpose is build a video management tools using face to classify videos.
So first step is extract images from videos.
First install ffmpeg, very easy:
brew install ffmpeg
After install ffmpeg, extract image is very easy:
ffmpeg -i xxx.mp4 -r 0.1 -f image2 image-%3d.jpeg
and more can see “How to extract images from a Video using FFmpeg“.
Our world, our future is rapidly changing. At the age of the Industrial Revolution, one invention can change the whole world, change the life style of all the people on the earth. But now, there are so many inventions can change our life. So, try to imagine what will happen.
For example, when Steve Jobs first announced iPhone on January 9, 2007, Nokia didn’t believe apple will be a strong competitor. But many years later, Nokia and Motorola both were acquired by other company.
People can predict it, It is very normal, in an industry, always some companies rise and others fall.
But at the very moment of iPhone birth, was there anyone can predict, because iPhone and other new smartphones rise, digital camera and digital video recorder industry will fall?
This is just the iPhone, but what next is auto drive car from Google, Dragon spacecraft from SpaceX, 3D printer, Tesla, Uber, Skybox Imaging, and so on. Any of these can change the whole world, so try to imagine all of these, and others we might not know yet.
I think we need: Open mind, quick learn and work hard.
After I heard about Uber, I have thinked it over and over.
And I ask almost every friends in the industry, “If 5 years ago you was chosen to improve the Taxi system by government or a big company, they and you want make the Taxi system more smart, have internet connect ability, what would you do?”
And I said,”I think you might want put some embed system on the Taxi, might chose x86 embed system or arm, and with 3G and wifi support, and have GPS. Did you?”
They usually said yes.
But Uber never need install any hardware on the car, every driver have a smart phone. And smart phone usually better than some kind embed system on you car.
Now let’s change a different perspective, at the age before Uber, how to organize all the taxi in a Taxi system?
We must build a call center, there are hundreds of agents deal with customer requests. When you call the Taxi company said you want a ride to airport, one of their agents will pick up you call, and send a radio broadcast to all the Taxi driver in the city. No matter how far away a Taxi to you, the driver can receive the broadcast, Whose dial first, get the job to pick you up.
This system have 3 problems. First is they can’t guarantee the Taxi nearby get the job, it is means you might have to wait a lot of time. Second is once a driver turn on the radio broadcast receiver, he must listen every broadcast, no matter far or near. Third is the most important one, is this system can’t easy scale up, because the limitation of human resources and telephone lines.
But how do Uber solve this problem? When you use Uber app to request a ride, there is no one pick up your call, just a server side application check your status, find the cars nearby, and send them information, if one of these cars response, then you get your ride. If not, system will send information to more faraway cars. So you are guaranteed get the most nearby car to pick you up.
Ok, I know today everyone can understand Uber and iPhone. But when iPhone just birthed, so many people said, “I will never buy this kind phone, it doesn’t even have a physical keyboard!!! “. But today, there are so many touch screen phone, and where is the physical keyboard?
We always think something familiar is normal, think anything unknown is odd, this is a part of our human nature. But this nature is harmful to us in this rapidly changing age.
We need try to put down prejudice to think deeper and think out of box, keep open mind.
Every technological revolution will tremendously improve productivity, so people are always wondering this will cause unemployment rise. But after times of technological revolution human race still keep reproduction and development, life on earth is better than ever.
When productivity improved, same job needs less workers, or same workers less work time. So there will be some unemployment. But people can get cheaper product and work less time. So, when people have more free time, they need entertainments, need social interacts. These needs give people the opportunity to develop entertainment industry and catering industry. And when these industries rise, they need workers, so unemployment problem is solved.
So, look at a very short period, you will think technological revolution will cause unemployment, but in a long period view, technological revolution only will cause labor redistribution. So, everyone lost jobs in the technological revolution age, isn’t because he can’t find any job, is because he can’t find a job he can participate in. He just don’t have the skill or learning ability.
Because 3D printer, auto drive car, this time, all the work relate to manual work will be replace by computer. So there will be very large unemployment, but at same time, factories and companies will need more and more programmers and operators to deal with the new computer system.
It will be a disaster, if you can’t learn anything new, and it will be a huge opportunity, if you can quick learn.
This isn’t need to talk a lot.
Everybody think himself, “Open mind, quick learn and work hard”, But there are not so many really are.
At 2009 when I first learned Objective-C and write my iOS app, it took me two weeks. I thought this was slow, but later notice that at that moment in Beijing, maybe only 20-100 people can write Objective-C code.
Three years later, I ask some of the people, they try again and again, but never learn how to write Objective-C code, “Why can’t you learn Objective-C?”
Someone said, “Mac is too expensive.”
Someone said, “I think Objective-C is too hard, I really can’t understand [object method]”
Someone said, “I need mentor, but I just can’t find one.”
And someone said, “I need be supervised.”
Then after some years, when swift come out, they said “I finally will learn how to write iOS app”, But I don’t think so.
Maybe swift is easy than Objective-C, but swift is odd too, if you can’t open mind to Objective-C, I think you can’t open mind to swift either.
No one will supervise you, if you want learn quick, you must learn how to self educate.
And, work hard is no meaning before you start.