你可以添加以下代码:

if(UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone){
        if ([[UIScreen mainScreen] respondsToSelector: @selector(scale)]) {
            CGSize result = [[UIScreen mainScreen] bounds].size;
            CGFloat scale = [UIScreen mainScreen].scale;
            result = CGSizeMake(result.width * scale, result.height * scale);

            if(result.height == 960) {
                NSLog(@"iPhone 4 Resolution");
            }
            if(result.height == 1136) {
              NSLog(@"iPhone 5 Resolution");
            }
        }
        else{
            NSLog(@"Standard Resolution");
        }
    }

值得注意的是，在新的Xcode中，你必须将这个图像文件Default-568h@2x.png添加到资产中

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.

要确定你的应用是否支持iPhone 5 Retina，请使用以下方法: (这可以更健壮地返回显示类型，4S视网膜等，但正如下面所写的，如果iPhone支持iOS5视网膜，它只返回YES或NO)

在一个普通的“。h”文件中添加:

BOOL IS_IPHONE5_RETINA(void);

在一个共同的”。M”文件添加:

BOOL IS_IPHONE5_RETINA(void) {
    BOOL isiPhone5Retina = NO;
    if(UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone) {
        if ([UIScreen mainScreen].scale == 2.0f) {
            CGSize result = [[UIScreen mainScreen] bounds].size;
            CGFloat scale = [UIScreen mainScreen].scale;
            result = CGSizeMake(result.width * scale, result.height * scale);

            if(result.height == 960){
                //NSLog(@"iPhone 4, 4s Retina Resolution");
            }
            if(result.height == 1136){
                //NSLog(@"iPhone 5 Resolution");
                isiPhone5Retina = YES;
            }
        } else {
            //NSLog(@"iPhone Standard Resolution");
        }
    }
    return isiPhone5Retina;
}

使用xCode 5，在项目>General上选择“迁移到资产目录”。

然后使用“Show in finder”找到你的启动图像，你可以模拟编辑它为640x1136，然后拖到资产目录，如下图所示。

确保iOS7和iOS6 R4部分都有一个640x1136的图像。下次你启动应用程序时，黑条将消失，你的应用程序将使用4英寸的屏幕

如果你需要将一个已经存在的应用程序转换为通用，你需要选择相应的xib文件->show Utilities-> show Size inspector。

在大小检查器中，你可以看到自动调整大小，通过使用这个工具你可以转换到现有的iOS应用程序。