1.利用UIImagePickeController可以从系统自带的App(照片,相册)中获取图片
2.设置代理,准守代理协议
*****注:UIImagePickerController类比较特殊,需要准守两个代理协议;

@interface ViewController () <UIImagePickerControllerDelegate, UINavigationControllerDelegate>  

3.实现代理的方法

#pragma mark  
#pragma mark - imagePicker的 代理方法  
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary<NSString *,id> *)info  

<span style="color:#333333;">- (IBAction)photo:(id)sender </span><pre name="code" class="objc">{  
    // 1.判断相册是否可以打开  
    if (![UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypePhotoLibrary]) return;  
    // 2. 创建图片选择控制器  
    UIImagePickerController *ipc = [[UIImagePickerController alloc] init];  
    /** 
     typedef NS_ENUM(NSInteger, UIImagePickerControllerSourceType) { 
     UIImagePickerControllerSourceTypePhotoLibrary, // 相册 
     UIImagePickerControllerSourceTypeCamera, // 用相机拍摄获取 
     UIImagePickerControllerSourceTypeSavedPhotosAlbum // 相簿 
     } 
     */  
    // 3. 设置打开照片相册类型(显示所有相簿)    
    ipc.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;  
    // ipc.sourceType = UIImagePickerControllerSourceTypeSavedPhotosAlbum;  
    // 照相机  
    // ipc.sourceType = UIImagePickerControllerSourceTypeCamera;  
    // 4.设置代理  
    ipc.delegate = self;  
    // 5.modal出这个控制器  
    [self presentViewController:ipc animated:YES completion:nil];  
}  

<span style="color:#333333;"></span><pre name="code" class="objc">#pragma mark -- <UIImagePickerControllerDelegate>--  
// 获取图片后的操作  
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary<NSString *,id> *)info  
{  
    // 销毁控制器  
    [picker dismissViewControllerAnimated:YES completion:nil];  
  
    // 设置图片  
    self.imageView.image = info[UIImagePickerControllerOriginalImage];  
}