UIImagePickerController简单剖析
概述
UIImagePickerController是苹果官方提供的一套相机、相册处理的方式。
使用UIImagePickerController你可以调用相机拍摄照片视频、调用相册功能。
下面详细介绍一下其相关的属性以及API，其中已经遗弃(DEPRECATED)的属性和方法将不再赘述
相关属性介绍
1.@property(nonatomic) UIImagePickerControllerSourceType sourceType; // default value is UIImagePickerControllerSourceTypePhotoLibrary.
资源类型，决定相机启用以后要跳转到哪个界面（相机拍照、照片图库、相册）
如下几种值
typedef NS_ENUM(NSInteger, UIImagePickerControllerSourceType) {
UIImagePickerControllerSourceTypePhotoLibrary, //照片图库
UIImagePickerControllerSourceTypeCamera, //相机
UIImagePickerControllerSourceTypeSavedPhotosAlbum //相册
}2.@property(nonatomic,copy) NSArray<NSString *> *mediaTypes;//默认值是 @[(NSString *)kUTTypeImage].
媒体类型，在相册模式的时候可以做一些筛选，筛选图片、视频、livephoto等各种不同类型的媒体。详细可设置参数见MobileCoreServices.framework的<MobileCoreServices/UTCoreTypes.h>
3.@property(nonatomic) BOOL allowsImageEditing
拍照结束后的是否允许编辑
4.@property(nonatomic) NSTimeInterval videoMaximumDuration
拍摄视频时的最大拍摄时间
5.@property(nonatomic) UIImagePickerControllerQualityType videoQuality
拍摄视频的质量
有如下几种值
typedef NS_ENUM(NSInteger, UIImagePickerControllerQualityType) {
UIImagePickerControllerQualityTypeHigh = 0, //最高质量
UIImagePickerControllerQualityTypeMedium = 1, //中质量，适合用WIFI传输
UIImagePickerControllerQualityTypeLow = 2, //低质量，可以用手机网络传输
UIImagePickerControllerQualityType640x480 = 3, // VGA质量 640x480
UIImagePickerControllerQualityTypeIFrame1280x720 = 4,
UIImagePickerControllerQualityTypeIFrame960x540 = 5,
}6.@property(nonatomic) BOOL showsCameraControls
是否显示系统默认相机UI界面（包括拍摄按钮、前后摄像头切换、闪光灯开关），默认为YES（显示系统默认UI），如果你需要自定义该界面，则需要隐藏该UI，设置自定义的UI给cameraOverlayView
7.@property(nullable, nonatomic,strong) __kindof UIView *cameraOverlayView
自定义相机遮盖层，可以自定义拍照框、拍照按钮、闪关灯、切换前后摄像头等UI，设置该属性是，同事需要将属性showsCameraControls设置为NO。
8.@property(nonatomic) CGAffineTransform cameraViewTransform
设置相机界面旋转
9.@property(nonatomic) UIImagePickerControllerCameraCaptureMode cameraCaptureMode
拍摄模式（拍摄照片或者拍摄视频）
下面两种值
typedef NS_ENUM(NSInteger, UIImagePickerControllerCameraCaptureMode) {
UIImagePickerControllerCameraCaptureModePhoto, //拍摄照片
UIImagePickerControllerCameraCaptureModeVideo //拍摄视频
}10.@property(nonatomic) UIImagePickerControllerCameraDevice cameraDevice
设置使用哪个硬件设备，前置摄像头或者后置摄像头
如下两种可选值
typedef NS_ENUM(NSInteger, UIImagePickerControllerCameraDevice) {
UIImagePickerControllerCameraDeviceRear, //后置摄像头
UIImagePickerControllerCameraDeviceFront //前置摄像头
}11.@property(nonatomic) UIImagePickerControllerCameraFlashMode cameraFlashMode
UIImagePickerControllerCameraFlashMode 闪光灯模式
关闭、自动、打开
如下两种可选值
typedef NS_ENUM(NSInteger, UIImagePickerControllerCameraFlashMode) {
UIImagePickerControllerCameraFlashModeOff = -1, //关闭
UIImagePickerControllerCameraFlashModeAuto = 0, //自动
UIImagePickerControllerCameraFlashModeOn = 1 //打开
}相关API方法介绍
1.- (void)takePicture
调用拍摄功能，即相机快门按钮所拥有的事件
2.- (BOOL)startVideoCapture
开始拍摄视频
3.- (void)stopVideoCapture
结束拍摄视频
UIImagePickerControllerDelegate代理方法介绍
1.- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary<NSString *,id> *)info
拍摄（照片、视频）、相机选取（照片、视频）结束之后的回调。
info里面的具体参数如下：
[info objectForKey:UIImagePickerControllerOriginalImage];
照片的原图[info objectForKey:UIImagePickerControllerEditedImage];
裁剪后的图[info objectForKey:UIImagePickerControllerCropRect];
图片裁剪后，剩下的图[info objectForKey:UIImagePickerControllerMediaURL]
图片在相册中的url[info objectForKey:UIImagePickerControllerMediaMetadata];
获取图片的metadata数据信息
可根据picker.sourceType来判断是相机拍摄之后的结果还是照片图库选择之后的结果,如果是照片图库的话，根据info里面的参数来判断是否是图片还是视频；如果是相机的话，再根据picker.cameraCaptureMode来判断拍摄的是图片还是视频，区别处理info信息，具体代码如下
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary<NSString *,id> *)info; {
if (picker.sourceType == UIImagePickerControllerSourceTypePhotoLibrary) {
if ([info valueForKey:UIImagePickerControllerOriginalImage]) {
UIImage *image = [info valueForKey:UIImagePickerControllerOriginalImage]; //原始图片
//处理图片信息`info` ...
}else{
//处理视频信息 `info` ...
NSLog(@"视频URL是：%@",[info valueForKey:UIImagePickerControllerMediaURL]);
}
}else{
if (picker.cameraCaptureMode == UIImagePickerControllerCameraCaptureModeVideo) {
//处理视频信息 `info`
NSLog(@"视频URL是：%@",[info valueForKey:UIImagePickerControllerMediaURL]);
}else{
UIImage *image = [info valueForKey:UIImagePickerControllerOriginalImage]; //原始图片
//处理图片信息`info` ...
}
}
NSLog(@"%@",info.description);
[picker dismissViewControllerAnimated:YES completion:nil];
}
PS：如果只是单单的拍照或者拍视频的话，上面的判断皆可以修改为你自己需要的就行
2.- (void)imagePickerControllerDidCancel:(UIImagePickerController *)picker
相机界面点击取消按钮的回调
里面写上如下代码即可退出相机界面
[imagePicker dismissViewControllerAnimated:YES completion:nil];相册存储相关API
1.UIKIT_EXTERN void UIImageWriteToSavedPhotosAlbum(UIImage *image, __nullable id completionTarget, __nullable SEL completionSelector, void * __nullable contextInfo)
将图片保存到相册
简单的使用：
- (void)saveImageToAlbum:(UIImage *)image {
UIImageWriteToSavedPhotosAlbum(image, self, @selector(imageSavedToPhotosAlbum:didFinishSavingWithError:contextInfo:), nil);
}
//保存照片成功后的回调
- (void)imageSavedToPhotosAlbum:(UIImage *)image didFinishSavingWithError:(NSError *)error
contextInfo:(void *)contextInfo {
if (!error) {
NSLog(@"保存图片到相册成功");
}else {
NSLog(@"保存图片到相册发生错误，错误信息%@",error);
}
}
2.UIKIT_EXTERN void UISaveVideoAtPathToSavedPhotosAlbum(NSString *videoPath, __nullable id completionTarget, __nullable SEL completionSelector, void * __nullable contextInfo)
将视频保存到相册
简单的使用：
- (void)saveVideoToAlbum:(NSString *)videoFilePath {
UISaveVideoAtPathToSavedPhotosAlbum(videoFilePath, self, @selector(videoSavedToPhotosAlbum:didFinishSavingWithError:contextInfo:), nil);
}
- (void)videoSavedToPhotosAlbum:(NSString *)videoPath didFinishSavingWithError:(NSError *)error
contextInfo:(void *)contextInfo{
if (!error) {
NSLog(@"保存视频到相册成功");
}else {
NSLog(@"保存视频到相册发生错误，错误信息%@",error);
}
}简单的使用代码如下：
- (void)showCamera {
UIImagePickerController *imagePicker = [[UIImagePickerController alloc] init];
imagePicker.delegate = (id)shareInstance;
imagePicker.sourceType = UIImagePickerControllerSourceTypeCamera;
//是否允许编辑照片
[imagePicker setAllowsEditing:YES];
//是否显示默认相机UI
[imagePicker setShowsCameraControls:YES];
[imagePicker setCameraDevice:UIImagePickerControllerCameraDeviceFront];
[imagePicker setCameraFlashMode:UIImagePickerControllerCameraFlashModeAuto];
//设置媒体类型
[self.imagePicker setMediaTypes:@[(NSString *)kUTTypeImage]];
//设置拍摄模式 （拍摄照片或者视频）
[self.imagePicker setCameraCaptureMode:UIImagePickerControllerCameraCaptureModePhoto];
//[self presentViewController:imagePicker animated:YES completion:NULL];
//需要请求权限，所以上一行行代码替换为：
[self showImagePicker];
}
PS：需要注意一点，在使用之前要向设备请求相机、相册权限，所以不能直接present，需要加上下面代码来请求权限
- (void) showImagePicker {
AVAuthorizationStatus authStatus = [AVCaptureDevice authorizationStatusForMediaType:AVMediaTypeVideo];
switch (authStatus) {
case AVAuthorizationStatusNotDetermined:{
[AVCaptureDevice requestAccessForMediaType:AVMediaTypeVideo completionHandler:^(BOOL granted){
if(granted){
[self presentViewController:imagePicker animated:YES completion:NULL];
}else{
[self showAlert:@"媒体(相机、相册)访问未授权"];
return;
}
}];
}
break;
case AVAuthorizationStatusAuthorized:
[self presentViewController:imagePicker animated:YES completion:NULL];
break;
default:
[self showAlert:@"请先在系统设置中对该应用开启相机、相册访问权限"];
break;
}
}PS：还需要注意一点，在使用之前在info.plist中添加相机请求的相关参数，xml代码如下
要使用设备相机拍照先要对应用开启相机、相册的访问权限，如果需要拍摄视频还需要开启麦克风访问权限。否则会直接crash。
xml代码如下
<key>NSPhotoLibraryUsageDescription</key>
<string>App需要您的同意,才能访问相册</string>
<key>NSCameraUsageDescription</key>
<string>App需要您的同意,才能访问相机</string>
<key>NSMicrophoneUsageDescription</key>
<string>App需要您的同意,才能访问麦克风</string>直接将上述xml复制粘贴到info.plist文件中即可。