How to Create a Global UIAlertController in Swift...

 Add this code in any Class (As UIViewController extension)  as shown below

extension UIViewController {

    

    func alert(message: String, title: String ) {

        let alertController = UIAlertController(title: title, message: message, preferredStyle: .alert)

        let OKAction = UIAlertAction(title: "OK", style: .default, handler: nil)

        alertController.addAction(OKAction)

        self.present(alertController, animated: true, completion: nil)

    }

    

}

and call it anywhere(In  Any ViewController) as shown below,

   self.alert(message: "Some message", title: "Title of Alert")

ActionSheet (AlertController) example...

ActionSheet (AlertController) example...

- (void)viewDidLoad {

    [super viewDidLoad];

    // Do any additional setup after loading the view, typically from a nib.    

    

    UIButton *btn = [UIButton buttonWithType:UIButtonTypeCustom];

    btn.frame = CGRectMake(120, 150, 60, 40);

    btn.backgroundColor = [UIColor redColor];

    btn.layer.borderWidth = 2;

    btn.layer.borderColor = [UIColor greenColor].CGColor;

    [btn setTitle:@"Press" forState:UIControlStateNormal];

    [btn setTitleColor:[UIColor blueColor] forState:UIControlStateNormal];

    btn.layer.cornerRadius = 10;

    [btn addTarget:self action:@selector(btnAction) forControlEvents:UIControlEventTouchUpInside];

    [self.view addSubview:btn];

    

}

- (void)btnAction {

   

    UIAlertController *alert = [UIAlertController alertControllerWithTitle:@"Directions"

                                                                   message:@"Select mode of transportation"

                                                            preferredStyle:UIAlertControllerStyleActionSheet];

    UIAlertAction *drivingAction = [UIAlertAction actionWithTitle:@"Driving" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {

        // this block runs when the driving option is selected

        NSLog(@"Clicked on Driving");

    }];

    UIAlertAction *walkingAction = [UIAlertAction actionWithTitle:@"Walking" style:UIAlertActionStyleDestructive handler:^(UIAlertAction * _Nonnull action) {

        // this block runs when the walking option is selected

        NSLog(@"Clicked on Walking");

    }];

    

    UIAlertAction *flyingAction = [UIAlertAction actionWithTitle:@"Flying" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {

        // this block runs when the walking option is selected

        NSLog(@"Clicked on Flying");

    }];

    

    UIAlertAction *defaultAction = [UIAlertAction actionWithTitle:@"Cancel" style:UIAlertActionStyleCancel handler:nil];

    [alert addAction:drivingAction];

    [alert addAction:walkingAction];

    [alert addAction:flyingAction];

    [alert addAction:defaultAction];

   

    [self presentViewController:alert animated:YES completion:nil];

}

AlertController With Textfields to login Validate...

AlertController With Textfields to login Validate...

Storyboard:

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController

- (IBAction)loginButtonTapped:(id)sender;

@end

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {

    [super viewDidLoad];

    // Do any additional setup after loading the view, typically from a nib.

    

}

- (void)didReceiveMemoryWarning {

    [super didReceiveMemoryWarning];

    // Dispose of any resources that can be recreated.

}

- (IBAction)loginButtonTapped:(id)sender {

    

    UIAlertController * alertController = [UIAlertController alertControllerWithTitle: @"Login"

                                                                              message: @"Input username and password"

                                                                       preferredStyle:UIAlertControllerStyleAlert];

  

    [alertController addTextFieldWithConfigurationHandler:^(UITextField *textField) {

        textField.placeholder = @"name";

        textField.textColor = [UIColor blueColor];

        textField.clearButtonMode = UITextFieldViewModeWhileEditing;

        textField.borderStyle = UITextBorderStyleRoundedRect;

    }];

    [alertController addTextFieldWithConfigurationHandler:^(UITextField *textField) {

        textField.placeholder = @"password";

        textField.textColor = [UIColor blueColor];

        textField.clearButtonMode = UITextFieldViewModeWhileEditing;

        textField.borderStyle = UITextBorderStyleRoundedRect;

        textField.secureTextEntry = YES;

    }];

    

    UIAlertAction *loginAction = [UIAlertAction actionWithTitle:@"LOGIN" style:UIAlertActionStyleDefault handler:^(UIAlertAction *action) {

        NSArray * textfields = alertController.textFields;

        UITextField * namefield = textfields[0];

        UITextField * passwordfiled = textfields[1];

        NSLog(@"%@:%@",namefield.text,passwordfiled.text);

        

        if ([namefield.text  isEqual: @"ravindar"] & [passwordfiled.text  isEqual: @"ravindar"]) {

            [alertController dismissViewControllerAnimated:YES completion:nil];

            

            // Write Code here to do whatever after Succesfull Login.....

            

        }else{

            [self presentViewController:alertController animated:YES completion:nil];

        

//            [alertController setTitle:@"Invalid Login"];

//            [alertController setMessage:@"Enter Correct Username or Password"];

            

            /* Above default Title & message is Present bt Over it added a View of label */

            UILabel *alertLbl = [[UILabel alloc]initWithFrame:CGRectMake(8, 8, 250, 55)];

            alertLbl.backgroundColor = [UIColor whiteColor];

            alertLbl.numberOfLines = 0;

            alertLbl.textAlignment = 1; //From Left 0, middle 1, Rught 2

            alertLbl.text = @"Enter Correct Username or Password";

            alertLbl.textColor = [UIColor redColor];

            [alertController.view addSubview:alertLbl];

            

            alertController.view.tintColor = [UIColor redColor]; // Action Title Color

        }

        

    }];

     [alertController addAction:loginAction];

     [self presentViewController:alertController animated:YES completion:nil];

//     loginAction.enabled = NO;

}

@end

Results:

AlertController with Table View & with Label inside it...

AlertController with Table View & with Label inside it...

StoryBoard...

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController

- (IBAction)alertWithLabelBtnTapped:(id)sender;

- (IBAction)alertWithTVBtnTapped:(id)sender;

@end

#import "ViewController.h"

@interface ViewController ()<UITableViewDelegate,UITableViewDataSource>

@end

@implementation ViewController

- (void)viewDidLoad {

    [super viewDidLoad];

    // Do any additional setup after loading the view, typically from a nib.

}

- (void)didReceiveMemoryWarning {

    [super didReceiveMemoryWarning];

    // Dispose of any resources that can be recreated.

}

- (IBAction)alertWithLabelBtnTapped:(id)sender {

    

    UIViewController *controller = [[UIViewController alloc]init];

    CGRect rect = CGRectMake(0, 0, 180, 50);

    [controller setPreferredContentSize:rect.size];

    UILabel *alertLbl = [[UILabel alloc]initWithFrame:CGRectMake(0, 0, 180, 40)];

    alertLbl.backgroundColor = [UIColor orangeColor];

    alertLbl.text = @" I am Alert Label";

    alertLbl.textColor = [UIColor greenColor];

    [controller.view addSubview:alertLbl];

    

    UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"Title" message:@"Message" preferredStyle:UIAlertControllerStyleAlert];

    [alertController setValue:controller forKey:@"contentViewController"];

    UIAlertAction *cancelAction = [UIAlertAction actionWithTitle:@"Cancel" style:UIAlertActionStyleDestructive handler:^(UIAlertAction *action) {

        

    }];

    [alertController addAction:cancelAction];

    [self presentViewController:alertController animated:YES completion:nil];

}

- (IBAction)alertWithTVBtnTapped:(id)sender {

    

    UIViewController *controller = [[UIViewController alloc]init];

    UITableView *alertTableView;

    

    CGRect rect = CGRectMake(0, 0, 280, 250);

    [controller setPreferredContentSize:rect.size];

    alertTableView  = [[UITableView alloc]initWithFrame:CGRectMake(0, 0, 280, 250)];

    

    alertTableView.delegate = self;

    alertTableView.dataSource = self;

    alertTableView.tableFooterView = [[UIView alloc]initWithFrame:CGRectZero];

    [alertTableView setSeparatorStyle:UITableViewCellSeparatorStyleSingleLine];

    [alertTableView setTag:1];

    [controller.view addSubview:alertTableView];

    [controller.view bringSubviewToFront:alertTableView];

    [controller.view setUserInteractionEnabled:YES];

    [alertTableView setUserInteractionEnabled:YES];

    [alertTableView setAllowsSelection:YES];

    UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"Title" message:@"Message" preferredStyle:UIAlertControllerStyleAlert];

    [alertController setValue:controller forKey:@"contentViewController"];

    UIAlertAction *cancelAction = [UIAlertAction actionWithTitle:@"Cancel" style:UIAlertActionStyleDestructive handler:^(UIAlertAction *action) {

        

    }];

    [alertController addAction:cancelAction];

    [self presentViewController:alertController animated:YES completion:nil];

    

}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section

{

    return 8;

}

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath

{

    return 40;

}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath

{

    static NSString *MyIdentifier = @"CellID";

    

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:MyIdentifier];

    if (!cell) {

        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:MyIdentifier] ;

    }

        cell.textLabel.text = @"Hellooo";

   

    return cell;

}

@end

Results: