Objective-C Language Blocks
Syntax
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// Declare as a local variable:
returnType (^blockName)(parameterType1, parameterType2, ...) = ^returnType(argument1, argument2, ...) {...};
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// Declare as a property:
@property (nonatomic, copy, nullability) returnType (^blockName)(parameterTypes);
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// Declare as a method parameter:
- (void)someMethodThatTakesABlock:(returnType (^nullability)(parameterTypes))blockName;
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// Declare as an argument to a method call:
[someObject someMethodThatTakesABlock:^returnType (parameters) {...}];
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// Declare as a typedef:
typedef returnType (^TypeName)(parameterTypes);
TypeName blockName = ^returnType(parameters) {...};
-
// Declare a C function return a block object:
BLOCK_RETURN_TYPE (^function_name(function parameters))(BLOCK_PARAMETER_TYPE);
Remarks
Blocks are specified by the Language Specification for Blocks for C, Objective-C, C++ and Objective-C++.
Additionally, the Blocks ABI is defined by the Block Implementation Specification.
