iOS Tutorial - Part 23 - UIAlertController, UIImagePickerController

UIAlertController, UIImagePickerController

Video Description 

UIAlertController

Displays an alert message to the user. This class replaces the UIActionSheet and UIAlertView classes for displaying alerts.

Steps to create UIAlertController

1- Initialize allertController with the specified title, message and the style you want.

    UIAlertController *alertCtrl = [UIAlertController alertControllerWithTitle:@"Alert Title" message:@"Alert Message" preferredStyle:UIAlertControllerStyleActionSheet];

2- Create actionAllert with specified title, style and handle the event when user taps on it

    UIAlertAction *buttonOnAlertCtrl = [UIAlertAction actionWithTitle:@"Button Title" style:UIAlertActionStyleDefault
                                                   handler:^(UIAlertAction *action)
                                                    {
                                                        //Handle Event
                                                    }];

3- Add the button to the allertController

[alertCtrl addAction:buttonOnAlertCtrl];

4- Show it to the screen

[self presentViewController:self.alertCtrl animated:YES completion:nil];

UIImagePickerController

You can use UIImagePickerController to get image from PhotoLibrary or Camera

Steps to get image from Camera

1- Create a property like bellow to access UIImagePickerController anywhere inside of your class @property (strong, nonatomic) UIImagePickerController *imagePicker; 2- Initialize and allocate memory

self.imagePicker = [[UIImagePickerController alloc] init];
//Set delegate method equal to self
self.imagePicker.delegate = self;
//Set source type (Here we choose camera)
self.imagePicker.sourceType = UIImagePickerControllerSourceTypeCamera;
//Present the camera to the screen
[self presentViewController:self.imagePicker animated:YES completion:nil];

2- Add delegate names (UIImagePickerControllerDelegate, UINavigationControllerDelegate) in front of the interface

@interface ViewController () 

3- Implement UIImagePickerControllerDelegate method

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
    NSData *dataImage = UIImageJPEGRepresentation([info objectForKey:@"UIImagePickerControllerOriginalImage"],1);
    UIImage *img = [[UIImage alloc] initWithData:dataImage];
    //img is the picture that user captured with the camera, you can do whatever you want with this picture
    //Add your own implementation here
}

Get get image from Photo Library

The steps are exactly like the steps for getting image from camera, except the source type. You should use the following line instead of line 4 of step 2:

    self.imagePicker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;

Write Macro to compile different block of code for simulator vs. actual device

If we want to tell the compiler to run a block of code if its simulator and other block of code if it's on actual device, we can use the following if else statement: #if TARGET_IPHONE_SIMULATOR //Put the block of code that you want to be executed if it's running on the simulator #elif TARGET_OS_IPHONE //Put the block of code that you want to be executed if it's running on the actual device #endif

All of the code for this tutorial

#import "ViewController.h"

@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:@"Camera"
                                                     style:UIAlertActionStyleDefault
                                                   handler:^(UIAlertAction *action)
                                                    {
                                                        [self handleCamera];
                                                    }];
    UIAlertAction *imageGallery = [UIAlertAction actionWithTitle:@"Image Gallery"
                                                     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];
    
}

Download

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