iOS 開發之 Fucking Block Syntax !

How Do I Declare A Block in Objective-C?

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) {...};
           

This is not intended to be an exhaustive list of all possible uses of blocks.

If you find yourself needing syntax not listed here, it is likely that a typedef would make your code more readable.

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