通过xib .........很容易迁移iPhone5和iPhone4

UIViewController *viewController3;
if ([[UIScreen mainScreen] bounds].size.height == 568)
{
    UIViewController *viewController3 = [[[mainscreenview alloc] initWithNibName:@"iphone5screen" bundle:nil] autorelease];               
}    
else
{
     UIViewController *viewController3 = [[[mainscreenview alloc] initWithNibName:@"iphone4screen" bundle:nil] autorelease];
}

Download and install latest version of Xcode. Set a Launch Screen File for your app (in the general tab of your target settings). This is how you get to use the full size of any screen, including iPad split view sizes in iOS 9. Test your app, and hopefully do nothing else, since everything should work magically if you had set auto resizing masks properly, or used Auto Layout. If you didn't, adjust your view layouts, preferably with Auto Layout. If there is something you have to do for the larger screens specifically, then it looks like you have to check height of [[UIScreen mainScreen] bounds] as there seems to be no specific API for that. As of iOS 8 there are also size classes that abstract screen sizes into regular or compact vertically and horizontally and are recommended way to adapt your UI.

在单例类中尝试下面的方法:

-(NSString *)typeOfDevice
    {
        if(UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone)
        {
            CGSize result = [[UIScreen mainScreen] bounds].size;
            if(result.height == 480)
            {
                return @"Iphone";
            }
            if(result.height == 568)
            {
                return @"Iphone 5";
            }
        }
        else{
            return @"Ipad";;
        }


        return @"Iphone";
    }

首先，创建两个xib并将所有委托，main类附加到xib，然后你可以在你的appdelegate中放入下面提到的条件。M文件在

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions 

    if ([[UIScreen mainScreen] bounds].size.height == 568)
        {

        self.ViewController = [[ViewController alloc] initWithNibName:@"ViewControlleriphone5" bundle:nil];
        }

        else
        {
             self.ViewController = [[ViewController alloc] initWithNibName:@"ViewControlleriphone4" bundle:nil];

        }

你可以在程序的任何地方使用它，这取决于你的需求，甚至在你的ViewController类中。最重要的是，您已经为iphone 4(320*480)和iphone 5(320*568)分别创建了两个xib文件。

有时候(对于预storyboard应用程序)，如果布局会有足够的不同，在viewController init中根据设备指定不同的xib是值得的(参见这个问题-你需要修改代码来处理iPhone 5)，因为如果你需要不同的图形，再多的自动调整蒙版也不会起作用。

-(id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil

    NSString *myNibName;
    if ([MyDeviceInfoUtility isiPhone5]) myNibName = @"MyNibIP5";
    else myNibName = @"MyNib";

    if ((self = [super initWithNibName:myNibName bundle:nibBundleOrNil])) {


...

这对于针对旧iOS版本的应用程序非常有用。

通过xib .........很容易迁移iPhone5和iPhone4

UIViewController *viewController3;
if ([[UIScreen mainScreen] bounds].size.height == 568)
{
    UIViewController *viewController3 = [[[mainscreenview alloc] initWithNibName:@"iphone5screen" bundle:nil] autorelease];               
}    
else
{
     UIViewController *viewController3 = [[[mainscreenview alloc] initWithNibName:@"iphone4screen" bundle:nil] autorelease];
}