苹果屏幕尺寸，像素，分辨率原文文档介绍地址：

https://www.paintcodeapp.com/news/ultimate-guide-to-iphone-resolutions

Objective-C 中 block块 的使用

http://fuckingblocksyntax.com

As a local variable:

returnType (^blockName)(parameterTypes) = ^returnType(parameters) {...};

As a property:

@property (nonatomic, copy, nullability) returnType (^blockName)(parameterTypes);

As a method parameter:

- (void)someMethodThatTakesABlock:(returnType (^nullability)(parameterTypes))blockName;

As an argument to a method call:

[someObject someMethodThatTakesABlock:^returnType (parameters) {...}];

As a typedef:

typedef returnType (^TypeName)(parameterTypes);

TypeName blockName = ^returnType(parameters) {...};