How Do I Declare A Block in Obje

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) {...};