UIImagePickerController-------

@UIImagePickerController 类是获取选择图片和视频的用户接口。我们可以用这个controller选择我们所需要的图片和视频。对于这个类来说比较特殊，我们不能够任意定制，也不可以继承生成子类。

1.当前设备是否支持使用UIImagePickerController，需要调用

     [UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera];

2.查看符合的媒体类型（图片或者视频,调用availableMediaTypesForSourceType: 方法判断。

3.sourceType(从哪选取媒体)

   // 打开图片库根目录选择
   UIImagePickerControllerSourceTypePhotoLibrary
   // 使用相机选择
   UIImagePickerControllerSourceTypeCamera
   // 打开SavedPhoto目录选择
   UIImagePickerControllerSourceTypeSavedPhotosAlbum

4.先创建一个UIImagePickerController(可以用模态推出相册或UIActionSheet推出)

@实现协议UIImagePickerControllerDelegate
_imagePickerC = [[UIImagePickerController alloc] init];  
_imagePickerC.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;  
_imagePickerC.allowsEditing = YES;  
_imagePickerC.delegate = self;  
[self presentModalViewController: _imagePickerC  animated: YES];  

    allowEditing 设置为YES，表示 允许用户编辑图片，否则，不允许用户编辑。

5.两个主要的委托方法

// 用户选中图片之后的回调
- (void)imagePickerController: (UIImagePickerController *)picker didFinishPickingMediaWithInfo: (NSDictionary *)info  
{  
    if (picker == picker_camera_)   
    {  
        //如果是 来自照相机的image，那么先保存  
        UIImage* original_image = [info objectForKey:@"UIImagePickerControllerOriginalImage"];  
    }
    
// info dictionary keys
UIKIT_EXTERN NSString *const UIImagePickerControllerMediaType;      // an NSString (UTI, i.e. kUTTypeImage)
UIKIT_EXTERN NSString *const UIImagePickerControllerOriginalImage;  // a UIImage
UIKIT_EXTERN NSString *const UIImagePickerControllerEditedImage;    // a UIImage
UIKIT_EXTERN NSString *const UIImagePickerControllerCropRect;       // an NSValue (CGRect)
UIKIT_EXTERN NSString *const UIImagePickerControllerMediaURL;       // an NSURL
UIKIT_EXTERN NSString *const UIImagePickerControllerReferenceURL    NS_AVAILABLE_IOS(4_1);  // an NSURL that references an asset in the AssetsLibrary framework
UIKIT_EXTERN NSString *const UIImagePickerControllerMediaMetadata   NS_AVAILABLE_IOS(4_1);  // an NSDictionary containing metadata from a captured photo
     
      
    // 获得编辑过的图片  
    UIImage* image = [info objectForKey: @"UIImagePickerControllerEditedImage"];  
    
    // 把图片转成NSData类型的数据来保存文件(存入到沙盒中)  
    NSData *imageData;  
    
    // 判断图片是不是png格式的文件  
    if (UIImagePNGRepresentation(image)) {  
    
        // 返回为png图像。  
        imageData = UIImagePNGRepresentation(image); 
         
    }else {  
    
       // 返回为JPEG图像
        imageData = UIImageJPEGRepresentation(image, 1.0);  
        
    }
    
    // 路径拼接,写入-----
    NSString * imageSavePath = [[[HMTMySqliteDataHandle shareInstance]saveImagesPath] stringByAppendingPathComponent:@"自定义.自定义"];
     
    [imageData writeToFile:imageSavePath atomically:YES];  
    
    // 关闭相册界面   
    [self dismissModalViewControllerAnimated:YES];  
    [picker release];  
} 

// 用户选择取消  
- (void) imagePickerControllerDidCancel: (UIImagePickerController *)picker  
{  
    // 关闭相册界面 
    [self dismissModalViewControllerAnimated:YES];  
    [picker release];  
}   

@ UIImagePickerController详解  

@  UIImagePickerController 任海丽(3G移动/开发)

@iOS摄像头和相册-UIImagePickerController-浅析