gistfile1.m

//UIAlertMode.h
#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>

typedef void (^AlertViewSelectionBlock) (NSInteger);
typedef void (^AlertControllerDefaultAction ) (UIAlertAction *);
typedef void (^AlertControllerCancelAction) (UIAlertAction *);
typedef void (^GenericBlock) (void *);

@interface UIAlertMode : NSObject

@property (assign, nonatomic) AlertViewSelectionBlock alertViewBlock;
@property (assign, nonatomic) AlertControllerCancelAction cancelAlertAction;
@property (assign, nonatomic) AlertControllerDefaultAction defaultAlertAction;

- (id) initAlertWith:(NSString *) title
                    :(NSString *) message
                    :(NSString *) cancelButtonTitle
                    :(NSString *) otherButtonTitle;


- (BOOL) supportsiOS8;
- (void) showAlertFor:(AlertViewSelectionBlock) alertViewBlock;
- (void) showAlertControllerFor:(AlertControllerDefaultAction) defaultAction :(AlertControllerCancelAction) cancelAction;
- (void) showAlertWith:(GenericBlock) block;
@end


// UIAlertMode.m

#import "UIAlertMode.h"
#import <objc/objc-runtime.h>
#import "AppDelegate.h"

@interface UIAlertMode () <UIAlertViewDelegate> {
    UIAlertView       *_alertView;
    UIAlertController *_alertController;
}

@end



@implementation UIAlertMode

@synthesize alertViewBlock;
@synthesize defaultAlertAction;
@synthesize cancelAlertAction;

- (id) init {
    self = [super init];
    return self;
}

- (id) initAlertWith:(NSString *) title
                    :(NSString *) message
                    :(NSString *) cancelButtonTitle
                    :(NSString *) otherButtonTitle {
    self = [super init];
    if ([self supportsiOS8]) {
        _alertController = [UIAlertController alertControllerWithTitle:title message:message preferredStyle:UIAlertControllerStyleAlert];
        
        UIAlertAction *defaultAction = [UIAlertAction actionWithTitle:otherButtonTitle style:UIAlertActionStyleDefault handler:^(UIAlertAction *action) {
            if (self.defaultAlertAction) {
                self.defaultAlertAction(action);
            }
        }];
        
        UIAlertAction *cancelAction = [UIAlertAction actionWithTitle:cancelButtonTitle style:UIAlertActionStyleCancel handler:^(UIAlertAction *action) {
            if (self.cancelAlertAction) {
                self.cancelAlertAction(action);
            }
        }];
        
        [_alertController addAction:defaultAction];
        [_alertController addAction:cancelAction];
        
    } else {
        _alertView = [[UIAlertView alloc] initWithTitle:title message:message delegate:self cancelButtonTitle:cancelButtonTitle otherButtonTitles:otherButtonTitle, nil];
    }
    return self;
}
#pragma mark - Public API

- (BOOL) supportsiOS8 {
    Class kAlertViewClass = NSClassFromString(@"UIAlertController");
    return !kAlertViewClass ? NO : YES;
}

- (void) showAlertFor:(AlertViewSelectionBlock) alertBlock {
    self.alertViewBlock = alertBlock;
    [_alertView show];
}
- (void) showAlertControllerFor:(AlertControllerDefaultAction) defaultAction :(AlertControllerCancelAction) cancelAction {
    self.cancelAlertAction = cancelAction;
    self.defaultAlertAction = defaultAction;
    dispatch_async(dispatch_get_main_queue(), ^{
        AppDelegate *delegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
        [delegate.window.rootViewController presentViewController:_alertController animated:YES completion:nil];
    });
}

#pragma mark - UIAlertView delegate method

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

@end