What is the use of UIScreen property in UIWindow?

Question

I was looking at the UIWindow class reference and there I found the UIScreen property which defaults to [UIScreen mainScreen]

@property(nonatomic,retain) UIScreen *screen NS_AVAILABLE_IOS(3_2);  
// default is [UIScreen mainScreen]. changing the screen may be an expensive operation and should not be done in performance-sensitive code

We initiailise the UIWindow object with the UIScreen in AppDelegate

self.window = [[UIWindow alloc] initWithFrame:[UIScreen mainScreen].bounds]

I am wondering why do we need the UIScreen property in UIWindow

Answer 1

UIScreen refers to the device frame.

https://developer.apple.com/library/ios/documentation/UIKit/Reference/UIScreen_Class/index.html

You can get the device size for finding the Devices iPhone 4,iPhone 5, iPhone 6, iPhone 6+ & iPad

[[UIScreen mainScreen] bounds] //gives u the size of the device.

You can differentiate the devices as per above sizes.

[[UIScreen mainScreen] bounds].size.width //gives the width of device [[UIScreen mainScreen] bounds].size.height) //gives the height of device.

Or you can use in this way

CGRect applicationFrame = [[UIScreen mainScreen] applicationFrame];

Hope it helps you...