Open Radar

 
Mapping an operation onto an array to create a new array is a very common problem that is unnecessarily cumbersome in ObjC. NSArray should have a built-in map-style methods such as:


Selector based (based on makeObjectsPerformSelector:): 

    - (NSArray *)arrayByApplyingSelector:(SEL)selector;
    - (NSArray *)arrayByApplyingSelector:(SEL)selector withObject:(id)argument;

    NSArray *names = [persons arrayByApplyingSelector:@selector(name)];


Block based (based on enumerateObjectsUsingBlock:):

    - (NSArray *)arrayByApplyingBlock:(id(^)(id obj, NSUInteger idx, BOOL *stop))block;

    NSArray *result = [numbers arrayByApplyingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
      return @([obj floatValue] + 5);
    }];


Function based (based on sortedArrayUsingFunction:...)

    - (NSArray *)arrayByApplyingFunction:(id (*)(id, void *))function context:(void *)context;