We are about to issue version 4.0 of our iPhone app and have had some complaints recently that previous versions are only available from iOS 4.1 plus. I know that to change this I can set my Deployment Target (In Project>Build) to iOS 3.1. However, I've run through the app on an emulator and again on my iPhone (uses iOS 4.2) but I'm not able to test on anything older as everyone here has the same iOS or 4.3. Can I safely assume that just by changing the Deployment Target and testing the app on later models that the app will run safely on later versions like 3.1.
We are familiar with the reason why people with older iPhones wont upgrade to iOS 4.0 and above, so we would like to accomodate them but not if it means the app is unsound and we have no way of testing it.
No, just because it compiles and runs on newer version of the SDK does not mean that it will work on older versions. If you're using features that are only available in iOS 4+ you'll need to check for their existence before using them; your app will crash otherwise.
There are some subtleties that you'll probably miss the first time too (or at least I did). In short, there's no real alternative to testing.
for the problem you have you need to install older versions of xcode having ios 3.0 support and you need to check whether it's working on the same or not as there are lots many changes in os 4.0 and above so it's definite that the application will not work with the ios 3.0, 3.1 available device and it will crashed.
Just install older version of SDK and test on simulator , if works then fine else you need to make code according to ios version 3.0 and ios version 4.0 in your code by differentiating the os and run the code accordingly.
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I have developed my app in Xcode 4.1 and iOS SDK version(Base SDK Version) is iOS 4.3 So, will this app run on iPhone with iOS 5 and/or iOS 6 or not?
I think the app can be run on a higher version of the OS than the Deployment Target. Is this right? I appreciate any help.
Yes, your app will run on anything that is iOS 4.3 or newer. That is, assuming you aren't using any depreciated methods that are removed from a future iOS release. You can check if things have been depreciated/removed through the documentation.
It doesn't matter with which Xcode you build your app, the base SDK signifies the lowest system your app is supporting.
You app can and will run on newer systems.
If you want to make an update to your app, you'll need to pay attention to depreciated methods for the newer systems or you will get rejected and won't be able to update in the App Store.
Yes, it will for sure run in higher versions than Deployment Target.
However, is always recommended to run also in newer versions as they are released, to check that every API used is still running fine (specially if they were deprecated).
If I build an app with the (default) iOS 5.1 SDK in XCode, and distribute it to the appstore, will users with, let's say, an iPhone 3G, be able to download and run the app?
It depends on what features you include in your app: if you use features that are only available in iOS5 such as UIPageController, then no, they will not be able to run it. However, if you don't use any feature of iOS 5, then it will most likely be ok.
Okay, let me answer you a little more correctly than Omar did:
In XCode, you can define both the SDK you're using to compile your app (should always be "latest" SDK, currently 5.1) and the Minimum OS Version that you're app will run with/at.
You should always test your app on all (Major) OS Versions starting from the defined minimum OS version.
You can react in your code to the current iOS Version and use different features depending on the currecnt version with a statement like:
if ([UIDevice systemVersionValue] >= 4.2f) {
// code for OSes at least as new as 4.2
} else {
// code for older OSs
}
If you want maximum exposure for your app, you should try to support all iOS Versions still supported by Apple. Currently, that's iOS 4.0 and newer, AFAIK. Given the very high update rate of iOS Users, everything older doesn't make much sense.
I can change my deployment target from 3.0 to 4.3 and test that my application is compatible with all these versions but how can I test if my application is compatible with all versions including iOS 5.0? Any idea regarding the same? Also note that I have iPhone 3GS with iOS 4.0.2 and need to test in iOS 5.0. Hope to get a good help. Thanks.
Eventually, you'll need to get a device that has iOS 5 installed. Without that, you can only test this in the iOS 5 simulator.
Also note that changing the deployment target is not enough to test if your app is compatible with that OS version. Basically, this just means that you promise that it'll run from this version upwards, but it doesn't enforce that you don't use any APIs that might not be available there.
I you wanna do it properly, you will have to get every device there is, with every version you want to support ... that is, imho, overkill. I just test my Apps on the 4.3 and 5.0 Simulator in XCode and on my 5.0 iPhone 4. And have not had any problems with that 'til now.
BTW you should update your 3GS to 5.0.1.
To test in the simulator with iOS5, you can set the OS version with the Version submenu of the simulator's Hardware menu.
I am writing an iPhone app in which I want to support the largest user base possible at this point in time (with minimal pain), so I decided that targeting IOS 4.3+ would be a good subset of users for my audience.
I started working in XCode 4.2, but reverted back to XCode 4.1 when I realized that the project templates had changed and everything seemed very intertwined with storyboarding, ARC, etc.
I have built out my application to the point I actually want to test on my device, which has iOS5 installed. When I attempt to use it though, I get this message as soon as I click 'use for development' in Organizer/XCode:
The project's build settings look like this:
My Question Is This: How do I get this application, built in XCode 4.1, to run on both iOS 4.3 and iOS 5 phones?
Are iOS SDKs not backward compatible? I come from Android development in which a less than current SDK will generally work on a newer SDK - is this different in the iOS world? And if so, how is this handled typically?
Any direction on how I should proceed would be greatly appreciated.
You can go ahead and open your app in Xcode 4.2 and it should still work. I've been working on a particular app since Xcode 3.x days and I'm nearly done, chugging along in Xcode 4.2 right now. It shouldn't be a problem. If you want to work with Xcode 4.1 you will be fine, but you won't be ale to use new features introduced in iOS 5.
There are several aspects of "cross-version" development to note.
Testing: You can only test on version of iOS that are included with your SDK, or that are installed on physical devices that you may have. The SDK generally comes only with the latest iOS, sometimes the previous one is included as well, but since Xcode 4 was released, the older SDKs have been progressively deprecated with each release. This is not to say that your app which is linked against the iOS 5 SDK won't run on older versions of iOS. It just depends on how you implement new features.
Features: In order to support older versions of iOS properly, you want to make sure that you don't implement new features without properly checking for the existence of classes, methods, and properties that were introduced in the newer versions of the OS. Unlike Android, you don't have to worry about a million hardware configurations. ;-)
Weak Linking: To support a new feature and still be compatible with older versions of iOS, you need to weak link against frameworks that you are using to implement new features. You can read more about that in the Apple Documentation on Weak Linking.
Deployment Target: The setting that prevents the app from loading on older devices is called the "Deployment Target". If you set this to 3.1.3, then your app will run on iOS 3.1.3 and higher. Remember that if you don't code the the proper version checking, your app may break.
ARC: You can choose to enable or disable Automatic Reference Counting when you create the project. ARC scans your program at compile time only, not at runtime, it doesn't break the app on older versions of the OS.
You need the latest version of XCode and the iOS SDK to install your apps onto your iOS 5.0 phone. That doesn't mean the inverse is true -- you don't need the same version of iOS on your device that you have installed on your computer.
Hope this helps!
You can use the latest SDK and simply set the "IOS Deployment Target" version to 4.3 in the project build settings.
XCode 4.1 doesn't support iOS5 in the sense that Xcode package doesn't contain the iOS5 SDK. So you must return to Xcode 4.2 and target your project for iOS 4.3 (you can also target it for iOS 4.0 with this Xcode version, but you will not be able to simulate it; you can even download older iOS 4.x package versions from the Xcode preferences menu if you really need to simulate them in your device).
You can opt-out of ARC if you want, this choice is given to you when you create the project, so don't worry; but consider that ARC does its magic at compile time only, not at runtime, so your backward compatibility will be kept if you decide to use this technology. Finally if you don't want Storyboard just pick the Empty app template and it will simply put in your project only the basic files. From this template you can create any iOS app, this is the approach I normally follow.
Should I be developing my app for 4.2?
Always use the latest SDK. Apple won't approve any apps built against 3.x anymore.
Edit:
There's a difference between the base SDK and the iOS you plan to support. You need to use the latest SDK as I stated before, however you may still create an app that runs on older versions of iOS by not using classes and methods that have been introduced in newer releases and setting the target OS appropriately.
Unless you have the need to support older iOS devices with older iOS versions, you should develop using 4.2 as it has a lot of features that are missing in 3.x. Most importantly: 3.x doesn't support multitasking.
Also, it's important to understand the relationship between Base SDK version and deployment target. In a nutshell: you can (and should) compile against the latest SDK version but if done correctly, you can still run the app on older iOS versions.
The base SDK should always be the latest version available (4.2 as of right now). Then you can use the deployment target to specify the minimum OS that your application will support, so a good rule of the thumb would be to use 3.0 for that.
Personally, I use some of new iOS 4.0 stuff (ie. GCD) a lot in my applications. I've heard that 90% of ios users are on 4.x. That should be a good middle ground.