iOS之相册实现

　　代码演示：

　　

- (IBAction)btAction:(UIButton *)sender {

    //创建提示框 控制器

    UIAlertController *alertC = [UIAlertController alertControllerWithTitle:@"提示框" message:nil preferredStyle:UIAlertControllerStyleActionSheet]; 

   //创建相机的点击事件按钮 

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

        //判断系统设备是否存在相机，有调用 没有提醒用户

        if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {

            //如果有摄像头 ,创建相机

            UIImagePickerController *picker = [[ UIImagePickerController alloc] init];

            //指定数据来源，来自于相机

            picker.sourceType = UIImagePickerControllerSourceTypeCamera;

            picker.delegate = self;

            picker.allowsEditing = YES;//允许编辑

            //使用模态弹出相机
            [self presentViewController:picker animated:YES completion:nil];

        }else {            
            //没有摄像头提醒用户，您的设备没有摄像头
            UIAlertController *controller = [UIAlertController alertControllerWithTitle:@"您的设备没有摄像头" message:nil preferredStyle:UIAlertControllerStyleAlert];

            UIAlertAction *action = [UIAlertAction actionWithTitle:@"确定" style:UIAlertActionStyleDefault handler:nil];

            [controller addAction:action];

            [self presentViewController:controller animated:YES completion:nil];
        }
    }];    
    [alertC addAction:alertA];//添加到提示框

   //创建相册的点击事件按钮，

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

        UIImagePickerController *picker = [[UIImagePickerController alloc] init];

        picker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;//指定数据来源是相册

        picker.delegate = self;

        picker.allowsEditing = YES;        

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

    }];    

    [alertC addAction:action];    

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

} 

//选取图片之后执行的方法
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary<NSString *,id> *)info{
    NSLog(@"%@",info);//是个字典 
   //通过字典的key值来找到图片  
    UIImage *image = [info objectForKey:UIImagePickerControllerOriginalImage];//并且赋值给声明好的imageView
    self.imageView.image = image;
  //最后模态返回 最初的 控制器
    [picker dismissViewControllerAnimated:YES completion:nil];
}