How Do I Declare A Block in Objective-C?

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于 2014-09-04 18:09:39 发布

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分类专栏： iOS 文章标签： ios block objective-c

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本文详细介绍了在Objective-C中声明Block的各种方法，包括作为局部变量、属性、方法参数、方法调用参数以及类型定义的方式。对于需要使用Block的Objective-C开发者来说，本文提供了实用的语法指导。

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How Do I Declare A Block in Objective-C?

As a local variable:

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

As a property:

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

As a method parameter:

- (void)someMethodThatTakesABlock:(returnType (^)(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.