According to me the best way of dealing with such problems and avoiding couple of condition required for checking the the height of device, is using the relative frame for views or any UI element which you are adding to you view for example: if you are adding some UI element which you want should at the bottom of view or just above tab bar then you should take the y origin with respect to your view's height or with respect to tab bar (if present) and we have auto resizing property as well. I hope this will work for you

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.

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。

唯一真正需要做的事情是在应用程序资源中添加一个名为“Default-568h@2x.png”的启动图像，在一般情况下(如果你足够幸运)应用程序将正常工作。

如果应用程序不处理触摸事件，那么确保键窗口有适当的大小。解决方法是设置适当的框架:

[window setFrame:[[UIScreen mainScreen] bounds]]

在迁移到iOS 6时，还有其他与屏幕大小无关的问题。详情请阅读iOS 6.0发布说明。

而不是使用一组条件，您可以自动调整您的视图使用屏幕大小。

int h = [[UIScreen mainScreen] bounds].size.height;
int w = [[UIScreen mainScreen] bounds].size.width;
self.imageView.frame = CGRectMake(20, 80, (h-200), (w-100));

在我的情况下，我想要一个视图，填补在顶部的一些输入字段和底部的一些按钮之间的空间，所以固定的左上角和变量右下角基于屏幕大小。我的应用程序用相机拍摄的照片填充图像视图，所以我想要尽可能多的空间。

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;
}