如何在OC中声明一个block?
作为一个本地变量:objc
returnType (^blockName)(parameterTypes) = ^returnType(parameters) {...};作为一个属性:
@property (nonatomic, copy, nullability) returnType (^blockName)(parameterTypes);
- (void)someMethodThatTakesABlock:(returnType (^nullability)(parameterTypes))blockName;
[someObject someMethodThatTakesABlock:^returnType (parameters) {...}];
typedef returnType (^TypeName)(parameterTypes);
TypeName blockName = ^returnType(parameters) {...};
 
                     
                     
                 
                        
                        