How do I handle the actions of a UIAlertController? - ios

Question

How can I link UIAlertController alert action buttons with action handlers using objective-c? I'm using Xcode 7.1.
Here is my code:
- (IBAction)selectbtn:(UIButton *)sender {
UIAlertController *alert=[ UIAlertController alertControllerWithTitle:#"NEW" message:#"button pressed" preferredStyle:UIAlertControllerStyleActionSheet];
UIAlertAction *cameraaction=[UIAlertAction actionWithTitle:#"From camera" style:UIAlertActionStyleDefault handler:nil ];
[alert addAction:cameraaction];
UIAlertAction *libraryaction=[UIAlertAction actionWithTitle:#"From photo library" style:UIAlertActionStyleDefault handler:nil ];
[alert addAction:libraryaction];
UIAlertAction *cancelaction=[UIAlertAction actionWithTitle:#"cancel" style:UIAlertActionStyleDestructive handler:nil];
[alert addAction:cancelaction];
[self presentViewController:alert animated:YES
completion:nil];
}

Answer 1

Objective-C
UIAlertController works like this:
UIAlertController *alert = [UIAlertController alertControllerWithTitle:#"Title" message:#"text mssg" preferredStyle:UIAlertControllerStyleAlert];
UIAlertAction *okAction = [UIAlertAction actionWithTitle:#"Ok" style:UIAlertActionStyleDefault handler:^(UIAlertAction * action){
// Ok action example
}];
UIAlertAction *otherAction = [UIAlertAction actionWithTitle:#"Other" style:UIAlertActionStyleDefault handler:^(UIAlertAction * action){
// Other action
}];
[alert addAction:okAction];
[alert addAction:otherAction];
[self presentViewController:alert animated:YES completion:nil];
I think you meant that.
Swift 3.0/4.0
let myalert = UIAlertController(title: "Titulo mensaje", message: "Mi mensaje.", preferredStyle: UIAlertControllerStyle.alert)
myalert.addAction(UIAlertAction(title: "Aceptar", style: .default) { (action:UIAlertAction!) in
print("Selected")
})
myalert.addAction(UIAlertAction(title: "Cancelar", style: .cancel) { (action:UIAlertAction!) in
print("Cancel")
})
self.present(myalert, animated: true)
Swift 5
let myalert = UIAlertController(title: "Titulo mensaje", message: "Mi mensaje.", preferredStyle: UIAlertController.Style.alert)
myalert.addAction(UIAlertAction(title: "Aceptar", style: .default) { (action:UIAlertAction!) in
print("Selected")
})
myalert.addAction(UIAlertAction(title: "Cancelar", style: .cancel) { (action:UIAlertAction!) in
print("Cancel")
})
self.present(myalert, animated: true)

Answer 2

You can add any code you want in the handler of the action method, sample code can be like this:
#interface ViewController () <UIImagePickerControllerDelegate, UINavigationControllerDelegate>
#property (weak, nonatomic) IBOutlet UIImageView *imageView;
#property (strong, nonatomic) UIAlertController *alertCtrl;
#property (strong, nonatomic) UIImagePickerController *imagePicker;
#end
#implementation ViewController
- (void)viewDidLoad
{
[super viewDidLoad];
[self setupAlertCtrl];
}
- (void) setupAlertCtrl
{
self.alertCtrl = [UIAlertController alertControllerWithTitle:#"Select Image"
message:nil
preferredStyle:UIAlertControllerStyleActionSheet];
//Create an action
UIAlertAction *camera = [UIAlertAction actionWithTitle:#"From camera"
style:UIAlertActionStyleDefault
handler:^(UIAlertAction *action)
{
[self handleCamera];
}];
UIAlertAction *imageGallery = [UIAlertAction actionWithTitle:#"From Photo Library"
style:UIAlertActionStyleDefault
handler:^(UIAlertAction *action)
{
[self handleImageGallery];
}];
UIAlertAction *cancel = [UIAlertAction actionWithTitle:#"Cancel"
style:UIAlertActionStyleCancel
handler:^(UIAlertAction *action)
{
[self dismissViewControllerAnimated:YES completion:nil];
}];
//Add action to alertCtrl
[self.alertCtrl addAction:camera];
[self.alertCtrl addAction:imageGallery];
[self.alertCtrl addAction:cancel];
}
- (IBAction)selectImagePressed:(UIButton *)sender
{
[self presentViewController:self.alertCtrl animated:YES completion:nil];
}
- (void)handleCamera
{
#if TARGET_IPHONE_SIMULATOR
UIAlertController *alert = [UIAlertController alertControllerWithTitle:#"Error"
message:#"Camera is not available on simulator"
preferredStyle:UIAlertControllerStyleAlert];
UIAlertAction *ok = [UIAlertAction actionWithTitle:#"OK"
style:UIAlertActionStyleDefault
handler:^(UIAlertAction *action)
{
[self dismissViewControllerAnimated:YES completion:nil];
}];
[alert addAction:ok];
[self presentViewController:alert animated:YES completion:nil];
#elif TARGET_OS_IPHONE
//Some code for iPhone
self.imagePicker = [[UIImagePickerController alloc] init];
self.imagePicker.delegate = self;
self.imagePicker.sourceType = UIImagePickerControllerSourceTypeCamera;
[self presentViewController:self.imagePicker animated:YES completion:nil];
#endif
}
- (void)handleImageGallery
{
self.imagePicker = [[UIImagePickerController alloc] init];
self.imagePicker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
self.imagePicker.delegate = self;
[self presentViewController:self.imagePicker animated:YES completion:nil];
}
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
NSData *dataImage = UIImageJPEGRepresentation([info objectForKey:#"UIImagePickerControllerOriginalImage"],1);
UIImage *img = [[UIImage alloc] initWithData:dataImage];
[self.imageView setImage:img];
[self.imagePicker dismissViewControllerAnimated:YES completion:nil];
}
Ref Link

Answer 3

UIAlertView Controller with multiple textFields.
#IBAction func showAlert(_ sender: UIButton) {
let alert = UIAlertController(title: "Registration", message: "Enter your name!", preferredStyle: .alert)
alert.addTextField { (textField1: UITextField) in
textField1.placeholder = "John"
}
alert.addTextField { (textField2: UITextField) in
textField2.placeholder = "Doe"
}
alert.addAction(UIAlertAction(title: "Ok", style: .default, handler: { (action: UIAlertAction) in
if let textField1 = alert.textFields?.first {
if textField1.text == "" {
print("you have to enter something first")
}else {
print("Hello \(textField1.text!)")
}
}
if let textField2 = alert.textFields?.first {
if textField2.text == "" {
print("you have to enter something first")
}else {
print("Hello \(textField2.text!)")
}
}
}))
alert.addAction(UIAlertAction(title: "Cancel", style: .cancel, handler: nil))
self.present(alert, animated: true, completion: nil)
}