import UIKit

class ViewController: UIViewController {
    // 1. define the variable that will hold our alert controller
    var controller:UIAlertController?
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // 2. start constructing a simple alert view controller using the alert view style
        controller = UIAlertController(title: "Title",
            message: "Message",
            preferredStyle: .Alert)
        
        // 3. simply print out a text to the console when pressed
        let action = UIAlertAction(title: "Done",
            style: UIAlertActionStyle.Default,
            handler: {
                (paramAction:UIAlertAction!) in
                println("The Done button was tapped")
            })
    
        // 4. add the action that we created to the alert controller
        controller!.addAction(action)
    }
    
    override func viewDidAppear(animated: Bool) {
        super.viewDidAppear(animated)
        
        // 5. present the alert controller
        self.presentViewController(controller!, animated: true, completion: nil)
    }
}

#import "ViewController.h"

@interface ViewController () <UIAlertViewDelegate>
@end

@implementation ViewController
...

- (void)viewDidAppear:(BOOL)animated {
    [super viewDidAppear:animated];
    
    self.view.backgroundColor = [UIColor whiteColor];
    
    NSString *message = @"Are you sure you want to open this link in Safari?";
    
    UIAlertView *alertView = [[UIAlertView alloc]
        initWithTitle:@"Open Link"
        message:message
        delegate:self
        cancelButtonTitle:@"No"
        otherButtonTitles:@"Yes", nil];
    
    [alertView show];
}

- (void) alertView:(UIAlertView *)alertView
    clickedButtonAtIndex:(NSInteger)buttonIndex {
    
    NSString *buttonTitle = [alertView buttonTitleAtIndex:buttonIndex];
    
    if ([buttonTitle isEqualToString:@"Yes"]){
        NSLog(@"User pressed the Yes button.");
    }
    else if ([buttonTitle isEqualToString:@"No"]){
        NSLog(@"User pressed the No button.");
    }
}