UIImagePickerController

UIImagePickerController简述：

UIImagePickerController 类是获取选择图片和视频的用户接口，我们可以用UIImagePickerController选择我们所需要的图片和视频。

注：UIImagePickerController不能够任意定制，也不可以继承生成子类。

一、UIImagePickerController的属性：

1、sourceType
指定使用模式（照相机/相册／照片库）
enum {
UIImagePickerControllerSourceTypePhotoLibrary,
UIImagePickerControllerSourceTypeCamera,
UIImagePickerControllerSourceTypeSavedPhotosAlbum
};

2、BOOL showsCameraControls
设置拍照时的下方的工具栏是否显示，如果需要自定义拍摄界面，则可把该工具栏隐藏。

3、BOOL allowsEditing
设置当拍照完或在相册选完照片后，是否跳到编辑模式进行图片剪裁
showsCameraControls=Yes时才有效果。

4、cameraDevice
判断设备是否支持前置摄像头／后置摄像头
enum {
     UIImagePickerControllerCameraDeviceRear,
     UIImagePickerControllerCameraDeviceFront
     };

5、cameraFlashMode
设置闪光灯模式
 enum {
     UIImagePickerControllerCameraFlashModeOff  = -1,
     UIImagePickerControllerCameraFlashModeAuto = 0,
     UIImagePickerControllerCameraFlashModeOn   = 1
     };

6、mediaTypes
设置相机支持的类型，拍照和录像
+ (NSArray *)availableMediaTypesForSourceType:(UIImagePickerControllerSourceType)sourceType
一共有三个可选的代理方法UIImagePickerControllerDelegate 
– imagePickerController:didFinishPickingMediaWithInfo:  
– imagePickerControllerDidCancel:  
– imagePickerController:didFinishPickingImage:editingInfo: 

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
info中包括选取的照片，视频的主要信息
NSString *const UIImagePickerControllerMediaType;         选取的类型 public.image  public.movie
NSString *const UIImagePickerControllerOriginalImage;    修改前的UIImage object.
NSString *const UIImagePickerControllerEditedImage;      修改后的UIImage object.
NSString *const UIImagePickerControllerCropRect;           原始图片的尺寸NSValue object containing a CGRect data type
NSString *const UIImagePickerControllerMediaURL;          视频在文件系统中 的 NSURL地址

7、cameraViewTransform
设置拍摄时屏幕的view的transform属性，可以实现旋转，缩放功能
enum{
CGAffineTransformMakeRotation；
CGAffineTransformMakeScale；
}

二、UIImagePickerController回调方法：

1、成功获得相片或视频后的回调

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info{
    //通过UIImagePickerControllerMediaType判断返回的是照片还是视频
    NSString* type = [info objectForKey:UIImagePickerControllerMediaType];
    //如果返回的type等于kUTTypeImage，代表返回的是照片,并且需要判断当前相机使用的sourcetype是拍照还是相册
    if ([type isEqualToString:(NSString*)kUTTypeImage]&&picker.sourceType==UIImagePickerControllerSourceTypeCamera) {
        //获取照片的原图
        UIImage* original = [info
        objectForKey:UIImagePickerControllerOriginalImage];
        //获取图片裁剪的图
        UIImage* edit = [info objectForKey:UIImagePickerControllerEditedImage];
        //获取图片裁剪后，剩下的图
        UIImage* crop = [info objectForKey:UIImagePickerControllerCropRect];
        //获取图片的url
        NSURL* url = [info objectForKey:UIImagePickerControllerMediaURL];
        //获取图片的metaData数据信息
        NSDictionary* metaData = [info objectForKey:UIImagePickerControllerMediaMetadata];
        //如果是拍照的照片，则需要手动保存到本地，系统不会自动保存拍照成功后的照片
        UIImageWriteToSavedPhotosAlbum(edit, self, @selector(image:didFinishSavingWithError:contextInfo:), nil);
    }else{

    }
    //模态方式退出uiimagepickercontroller
    [imagepicker dismissModalViewControllerAnimated:YES];
}

2、取消照相机的回调

- (void)imagePickerControllerDidCancel:(UIImagePickerController *)picker{
     //模态方式退出UIImagePickerController
     [imagePicker dismissModalViewControllerAnimated:YES];
 }

3、保存照片成功后的回调

- (void)image:(UIImage *)image didFinishSavingWithError:(NSError *)error
   contextInfo:(void *)contextInfo{
     
 }