Question

Hey,
I m developing an iPhone application and my target is 3GS and 4G devices.
iOS 4 introduces methods thats deal with multitasking and newer methods to deal with foreground/background lifecycle events.
These new methods aren t available in iOS 3 which simply quits the app and doesn t run it in the background.
Any tips on how to create apps that run on iOS 3 and iOS 4?

Answer 1

iPad方案规划指南(我知道,不是你所期望的)有一节是关于世界观的内容,表明你如何控制在运行时存在象征。这也适用于你的问题。

Start here: https://developer.apple.com/library/ios/documentation/General/Conceptual/iPadProgrammingGuide/StartingYourProject/StartingYourProject.html#//apple_ref/doc/uid/TP40009370-CH9-SW3

Answer 2

我把我的所有系列文件都放在一个部分,然后把一个编汇的宏观(代号为你们汇编),并在每个职能范围内进行功能检查(一旦编辑,你的代码便没有坠毁)。

    //Define Logic for conditional code based on version of iOS
#if __IPHONE_OS_VERSION_MAX_ALLOWED >= 40000
- (void)applicationDidEnterBackground:(UIApplication *)application {
    //SPECIAL CASE:For OS versions before 4.0, background processes are not supported
    if (backgroundSupported) {
         <IOS4 CODE GOES HERE>
    }
}

- (void)applicationWillEnterForeground:(UIApplication *)application {
    if (backgroundSupported) {
        if (backgroundSupported) {
         <IOS4 CODE GOES HERE>
    }
}

- (BOOL)checkBackgroundSupported {
    UIDevice* device = [UIDevice currentDevice];
    backgroundSupported = NO;
    if ([device respondsToSelector:@selector(isMultitaskingSupported)])
        backgroundSupported = device.multitaskingSupported;
    return backgroundSupported;
}
#endif

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