[转]How Do I Declare A Block in Objective-C?

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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 site 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.Unable to access this site due to the profanity in the URL? http://goshdarnblocksyntax.com is a more work-friendly mirror.