Objective-C Language Blocks Block Typedefs
Example
typedef double (^Operation)(double first, double second);
If you declare a block type as a typedef, you can then use the new type name instead of the full description of the arguments and return values. This defines Operation as a block that takes two doubles and returns a double.
The type can be used for the parameter of a method:
- (double)doWithOperation:(Operation)operation
first:(double)first
second:(double)second;
or as a variable type:
Operation addition = ^double(double first, double second){
return first + second;
};
// Returns 3.0
[self doWithOperation:addition
first:1.0
second:2.0];
Without the typedef, this is much messier:
- (double)doWithOperation:(double (^)(double, double))operation
first:(double)first
second:(double)second;
double (^addition)(double, double) = // ...
