iOS开发之调用手机摄像头和相册

//按钮的点击方法
- (void)catchImage {

    UIAlertController *alert = [UIAlertController alertControllerWithTitle:@"请选择" message:@"选取照片" preferredStyle:UIAlertControllerStyleAlert];
    
    UIAlertAction *action1 = [UIAlertAction actionWithTitle:@"相机" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
        
        if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {
            
            UIImagePickerController *picker = [[UIImagePickerController alloc] init];
            picker.sourceType = UIImagePickerControllerSourceTypeCamera;
            picker.delegate = self;
            picker.allowsEditing = YES;
            [self presentViewController:self animated:YES completion:nil];
            
        } else {
            
            UIAlertController *controller = [UIAlertController alertControllerWithTitle:@"没有摄像头" message:nil preferredStyle:UIAlertControllerStyleActionSheet];
            UIAlertAction *action = [UIAlertAction actionWithTitle:@"确定" style:UIAlertActionStyleDestructive handler:nil];
            [controller addAction:action];
            [self presentViewController:controller animated:YES completion:nil];
        }
    }];
    [alert addAction:action1];
    UIAlertAction *action2 = [UIAlertAction actionWithTitle:@"相册" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
        
        UIImagePickerController *picker = [[UIImagePickerController alloc] init];
        picker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
        picker.delegate = self;
        picker.allowsEditing = YES;
        [self presentViewController:picker animated:YES completion:nil];
    }];
    [alert addAction:action2];
    [self presentViewController:alert animated:YES completion:nil];

}

//选取图片之后执行的方法
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary<NSString *,id> *)info {

    UIImage *image = [info objectForKey:UIImagePickerControllerOriginalImage];
    self.imageView.image = image;
    [picker dismissViewControllerAnimated:YES completion:nil];

}


- (void)viewDidLoad {
    [super viewDidLoad];
    
    _button = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    [_button setTitle:@"选取头像" forState:UIControlStateNormal];
    _button.frame = CGRectMake(100, 100, 100, 30);
    [_button addTarget:self action:@selector(catchImage) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:_button];
    
    _imageView = [[UIImageView alloc] initWithFrame:CGRectMake(100, 250, 150, 150)];
    _imageView.backgroundColor = [UIColor yellowColor];
    [self.view addSubview:_imageView];
    
    
    
    // Do any additional setup after loading the view.
}