AlertViewCallback.m

@interface AlertViewCallback : NSObject <UIAlertViewDelegate>
@property (copy, nonatomic) void (^callback)(void);
@end

@implementation AlertViewCallback

+ (instancetype)callback:(void (^)(void))callback {
    return [[self alloc] initWithCallback:callback];
}

- (instancetype)initWithCallback:(void (^)(void))callback {
    self = [super init];
    if (self) {
        self.callback = callback;
    }
    return self;
}

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex {
    self.callback();
}

@end