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iOS控件之UIImagePickerController

iOS控件之UIImagePickerController

作者: pican | 来源:发表于2015-09-25 17:05 被阅读12921次

    UIImagePickerController是iOS系统提供的和系统的相册和相机交互的一个类,可以用来获取相册的照片,也可以调用系统的相机拍摄照片或者视频。该类的继承结构是:

    UIImagePickerController-->UINavigationController-->UIViewController-->UIResponder-->NSObject

    官方文档中对于该类的说明是:

    该类只支持竖屏模式,为了保证该类被原样使用,它不支持子类,并且它的视图层次是私有的不能被修改,只支持自定义cameraOverlayView属性来展示更多信息以及和用户的交互。

    由于该类继承自UINavgationController,所以在使用过程中一般实现UIImagePickerControllerDelegateUINavigationControllerDelegate这两个代理,可以利用navgation的push 和pop操作自定义界面实现更复杂的交互效果。下面具体分析该类的一些方法和属性.

    • 属性


      @property(nullable,nonatomic,weak) id <UINavigationControllerDelegate, UIImagePickerControllerDelegate> delegate;
    

    该对象的代理需要实现UINavigationControllerDelegate和UIImagePickerControllerDelegate协议,nullable是xcode6.3之后引入的nullability annotations特性,主要用于在OC和swift之间的转换。这一特性主要包含两个新的类型注释__nullable和__nonnull,用于表示对象是否可以是NULL或nil(具体内容请参考Xcode特性之nullability annotayions)

    @property(nonatomic)  UIImagePickerControllerSourceType     sourceType;  // default value is UIImagePickerControllerSourceTypePhotoLibrary.```
    sourceType用于指定要访问的系统的媒体类型。UIImagePickerControllerSourceType支持以下3种枚举类型,默认值是图片库  
    

    typedef NS_ENUM(NSInteger, UIImagePickerControllerSourceType) {
    UIImagePickerControllerSourceTypePhotoLibrary,
    UIImagePickerControllerSourceTypeCamera,
    UIImagePickerControllerSourceTypeSavedPhotosAlbum
    };```
    PhotoLibrary代表系统照片应用对应的相薄,包含照片流和其它自定义的相册,PhotosAlbum则对应系统照片应用的照片,包含用设备拍摄的所有照片流。Camera则代表相机的摄像头。

     @property(nonatomic,copy)      NSArray<NSString *>  *mediaTypes;```
    mediaTypes用于设置相机支持的功能,拍照或者是视频,返回值类型可以是kUTTypeMovie,kUTTypeImage   
    

    @property(nonatomic) BOOL showsCameraControls NS_AVAILABLE_IOS(3_1);
    @property(nonatomic) BOOL allowsEditing NS_AVAILABLE_IOS(3_1); // replacement for -allowsImageEditing; default value is NO.
    @property(nonatomic) BOOL allowsImageEditing NS_DEPRECATED_IOS(2_0, 3_1);```
    showsCameraControls用于指定拍照时下方的工具栏是否显示,allowImageEditing在iOS3.1就已废弃,取而代之的是allowEditing,表示拍完照片或者从相册选完照片后,是否跳转到编辑模式对图片裁剪,只有在showsCameraControls为YES时才有效果。

    @property(nonatomic) UIImagePickerControllerCameraCaptureMode cameraCaptureMode NS_AVAILABLE_IOS(4_0); // default is UIImagePickerControllerCameraCaptureModePhoto
    @property(nonatomic) UIImagePickerControllerCameraDevice      cameraDevice      NS_AVAILABLE_IOS(4_0); // default is UIImagePickerControllerCameraDeviceRear
    @property(nonatomic) UIImagePickerControllerCameraFlashMode   cameraFlashMode 
    @property(nullable, nonatomic,strong) __kindof UIView  *cameraOverlayView  NS_AVAILABLE_IOS(3_1);   // set a view to overlay the preview view.
    @property(nonatomic)   CGAffineTransform    cameraViewTransform NS_AVAILABLE_IOS(3_1);   // set the transform of the preview view.```
    当sourceType是camera的时候,这几个属性有限,否则抛出异常。cameraCaptureMode捕捉模式指定的是相机是拍摄照片还是视频,它的枚举类型如下:   
    

    NS_ENUM(NSInteger, UIImagePickerControllerCameraCaptureMode) {
    UIImagePickerControllerCameraCaptureModePhoto,//photo
    UIImagePickerControllerCameraCaptureModeVideo//video
    };```
    cameraDevice指定拍摄的摄像头位置,是使用前置摄像头还是后置摄像头,它的枚举类型有:

    typedef NS_ENUM(NSInteger, UIImagePickerControllerCameraDevice) {
        UIImagePickerControllerCameraDeviceRear,
        UIImagePickerControllerCameraDeviceFront
    };```
    cameraFlashMode用于指定闪光灯模式,它的枚举类型如下:
    

    typedef NS_ENUM(NSInteger, UIImagePickerControllerCameraFlashMode) {
    UIImagePickerControllerCameraFlashModeOff = -1,
    UIImagePickerControllerCameraFlashModeAuto = 0,
    UIImagePickerControllerCameraFlashModeOn = 1
    };```
    cameraViewTransform该结构体可以用于指定拍摄时View的一些形变属性,如旋转缩放等。
    当showsCameraControls为NO,系统的工具栏隐藏时,我们可以自定义背景View赋值给cameraOverlayView添加到拍摄时的预览视图之上。

    @property(nonatomic)  NSTimeInterval     videoMaximumDuration NS_AVAILABLE_IOS(3_1); // default value is 10 minutes.
    @property(nonatomic)  UIImagePickerControllerQualityType    videoQuality NS_AVAILABLE_IOS(3_1); ```
    
    videoMaximumDuration用于设置视频拍摄模式下最大拍摄时长,默认值是10分钟。 videoQuality表示拍摄的视频质量设置,默认是Medium即表示中等质量。 videoQuality支持的枚举类型如下:
    

    typedef NS_ENUM(NSInteger, UIImagePickerControllerQualityType) {
    UIImagePickerControllerQualityTypeHigh = 0, // 高清模式
    UIImagePickerControllerQualityTypeMedium = 1, //中等质量,适于WIFI传播
    UIImagePickerControllerQualityTypeLow = 2, //低等质量,适于蜂窝网络传输
    UIImagePickerControllerQualityType640x480 NS_ENUM_AVAILABLE_IOS(4_0) = 3, // VGA 质量
    UIImagePickerControllerQualityTypeIFrame1280x720 NS_ENUM_AVAILABLE_IOS(5_0) = 4,//1280720的分辨率
    UIImagePickerControllerQualityTypeIFrame960x540 NS_ENUM_AVAILABLE_IOS(5_0) = 5,//960
    540分辨率
    };```

    • 类方法


     @interface UIImagePickerController : UINavigationController   <NSCoding>
    + (BOOL)isSourceTypeAvailable:(UIImagePickerControllerSourceType)sourceType;                 // returns YES if source is available (i.e. camera present)
    + (nullable NSArray<NSString *> *)availableMediaTypesForSourceType:(UIImagePickerControllerSourceType)sourceType; // returns array of available media types (i.e. kUTTypeImage)
    + (BOOL)isCameraDeviceAvailable:(UIImagePickerControllerCameraDevice)cameraDevice                   NS_AVAILABLE_IOS(4_0); // returns YES if camera device is available 
    + (BOOL)isFlashAvailableForCameraDevice:(UIImagePickerControllerCameraDevice)cameraDevice           NS_AVAILABLE_IOS(4_0); // returns YES if camera device supports flash and torch.
    + (nullable NSArray<NSNumber *> *)availableCaptureModesForCameraDevice:(UIImagePickerControllerCameraDevice)cameraDevice NS_AVAILABLE_IOS(4_0);
    

    isSourceTypeAvailable用于判断当前设备是否支持指定的sourceType,可以是照片库/相册/相机.
    isCameraDeviceAvailable判断当前设备是否支持前置摄像头或者后置摄像头
    isFlashAvailableForCameraDevice是否支持前置摄像头闪光灯或者后置摄像头闪光灯
    availableMediaTypesForSourceType方法返回所特定的媒体如相册/图片库/相机所支持的媒体类型数组,元素值可以是kUTTypeImage类型或者kUTTypeMovie类型的静态字符串,所以是NSString类型的数组
    availableCaptureModesForCameraDevice返回特定的摄像头(前置摄像头/后置摄像头)所支持的拍摄模式数值数组,元素值可以是UIImagePickerControllerCameraCaptureMode枚举里面的video或者photo,所以是NSNumber类型的数组


    • 对象方法

      - (void)takePicture NS_AVAILABLE_IOS(3_1);
      - (BOOL)startVideoCapture NS_AVAILABLE_IOS(4_0);
      - (void)stopVideoCapture  NS_AVAILABLE_IOS(4_0);
      

    takePicture可以用来实现照片的连续拍摄,需要自己自定义拍摄的背景视图来赋值给cameraOverlayView ,结合自定义overlayView实现多张照片的采集,在收到代理的didFinishPickingMediaWithInfo方法之后可以启动额外的捕捉。
    startVideoCapture用来判断当前是否可以开始录制视频,当视频正在拍摄中,设备不支持视频拍摄,磁盘空间不足等情况,该方法会返回NO.该方法结合自定义overlayView可以拍摄多部视频
    stopVideoCapture当你调用此方法停止视频拍摄时,它会调用代理的imagePickerController:didFinishPickingMediaWithInfo:方法


    • 代理方法

      @protocol  UIImagePickerControllerDelegate<NSObject>
      @optional
      - (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingImage:(UIImage *)image editingInfo:(nullable NSDictionary<NSString *,id> *)editingInfo NS_DEPRECATED_IOS(2_0, 3_0);
      - (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary<NSString *,id> *)info;
      - (void)imagePickerControllerDidCancel:(UIImagePickerController *)picker;
      @end
      

    imagePickerController:didFinishPickingImage:editingInfo:在iOS3.0中已废弃,不再使用。当用户取消选取的内容时会调用DidCancel方法,默认实现销毁弹出的视图。当完成内容的选取时会调用didFinishPickingMediaWithInfo方法,默认info字典的key值可以是以下类型:

    UIKIT_EXTERN NSString *const UIImagePickerControllerMediaType;      //指定用户选择的媒体类型
    UIKIT_EXTERN NSString *const UIImagePickerControllerOriginalImage;  // 原始图片
    UIKIT_EXTERN NSString *const UIImagePickerControllerEditedImage;    // 修改后的图片
    UIKIT_EXTERN NSString *const UIImagePickerControllerCropRect;       // 裁剪尺寸
    UIKIT_EXTERN NSString *const UIImagePickerControllerMediaURL;       // 媒体的URL
    UIKIT_EXTERN NSString *const UIImagePickerControllerReferenceURL        NS_AVAILABLE_IOS(4_1);  // 原件的URL
    UIKIT_EXTERN NSString *const UIImagePickerControllerMediaMetadata //当数据来源是相机的时候获取到的静态图像元数据,可以使用phtoho框架进行处理
    

    • C函数(保存照片或视频)

    UIKIT_EXTERN void UIImageWriteToSavedPhotosAlbum(UIImage *image, __nullable id completionTarget, __nullable SEL completionSelector, void * __nullable contextInfo);
    UIKIT_EXTERN BOOL UIVideoAtPathIsCompatibleWithSavedPhotosAlbum(NSString *videoPath) NS_AVAILABLE_IOS(3_1);
    UIKIT_EXTERN void UISaveVideoAtPathToSavedPhotosAlbum(NSString *videoPath, __nullable id completionTarget, __nullable SEL completionSelector, void * __nullable contextInfo) NS_AVAILABLE_IOS(3_1);
    

    UIImageWriteToSavedPhotosAlbum用来保存照片到相册,seletor应该设置为- (void)image:(UIImage *)image didFinishSavingWithError:(NSError *)error contextInfo:(void *)contextInfo;当照片保存到相册完成时,会调用该方法通知你。
    UIVideoAtPathIsCompatibleWithSavedPhotosAlbum会返回布尔类型的值判断该路径下的视频能否保存到相册,视频需要先存储到沙盒文件再保存到相册,而照片是可以直接从代理完成的回调info字典里面获取到。
    UISaveVideoAtPathToSavedPhotosAlbum用来保存视频到相册,seletor应该设置为- (void)video:(NSString *)videoPath didFinishSavingWithError:(NSError *)error contextInfo:(void *)contextInfo;当视频保存到相册或出错时会调用该方法通知你。
    这三个方法一般是在代理的完成方法didFinishPickingMediaWithInfo里面配合使用。


    关于编辑照片界面的英文,可以在info.plist设置Localized resources can be mixed 的值为YES就可以转换为你当前系统的语言。更多关于info.plist的详解请参考iOS系统配置info.plist下面是关于使用UIImagePickerConreoller来上传头像,照片多选以及拍摄视频的一个Demo

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