Blocks instead of delegates

blocks_not_delegates.mm

// Widget.h
 
#import <UIKit/UIKit.h>
 
@interface Widget : UIView
@property (nonatomic, copy) void (^action)(Widget *widget, NSUInteger someArg);
@end
 
// Widget.m
 
#import "Widget.h"
 
// ...
 
- (void)somethingHappenedWithArgument:(NSUInteger)arg
{
    if (self.action) self.action(self, arg);
}
 
// usage in ViewController.m:
 
{
    __weak ViewController *weak = self;
    Widget *widget = ...;
    widget.action = ^(Widget *widget, NSUInteger someArg) {
        ViewController *self = weak;
        [self updateStateWithArg:someArg];
    };
}