iOS 调用相机和相册详解

在一些应用中，我们需要用到iOS设备的摄像头进行拍照，视频。并且从相册中选取我们需要的图片或者视频。关于iOS摄像头和相册的应用，可以使用UIImagePickerController类来完成控制。

关于UIImagePickerController的相关知识，如下：

iOS的一些设备上都安装了摄像头。现在绝大多数都有了。在编程中，我们是用相应的东西来进行照相，录像等功能。

一、UIImagePickerController类

UIImagePickerController 这个类可以为大家提供照相的功能,以及图片,视频浏览的功能。

二、检查硬件是否安装有摄像头或者允许操作相册 

这些公共的方法，我们也许会用到，我就贴了！So easy！！！

 #pragma mark - 摄像头和相册相关的公共类

 // 判断设备是否有摄像头
 - (BOOL) isCameraAvailable{
     return [UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera];
 }

 // 前面的摄像头是否可用
 - (BOOL) isFrontCameraAvailable{
     return [UIImagePickerControllerisCameraDeviceAvailable:UIImagePickerControllerCameraDeviceFront];
 }

 // 后面的摄像头是否可用
 - (BOOL) isRearCameraAvailable{
     return [UIImagePickerControllerisCameraDeviceAvailable:UIImagePickerControllerCameraDeviceRear];
 }


 // 判断是否支持某种多媒体类型：拍照，视频
 - (BOOL) cameraSupportsMedia:(NSString *)paramMediaType sourceType:(UIImagePickerControllerSourceType)paramSourceType{
     __block BOOL result = NO;
     if ([paramMediaType length] == 0){
         NSLog(@"Media type is empty.");
         return NO;
     }
     NSArray *availableMediaTypes =[UIImagePickerControlleravailableMediaTypesForSourceType:paramSourceType];
     [availableMediaTypes enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL*stop) {
                                                         NSString *mediaType = (NSString *)obj;
                                                         if ([mediaTypeisEqualToString:paramMediaType]){
                                                             result = YES;
                                                             *stop= YES;
                                                         }

     }];
     return result;
 }

 // 检查摄像头是否支持录像
 - (BOOL) doesCameraSupportShootingVideos{
     return [self cameraSupportsMedia:( NSString *)kUTTypeMoviesourceType:UIImagePickerControllerSourceTypeCamera];
 }

 // 检查摄像头是否支持拍照
 - (BOOL) doesCameraSupportTakingPhotos{
     return [self cameraSupportsMedia:( NSString *)kUTTypeImagesourceType:UIImagePickerControllerSourceTypeCamera];
 }

 #pragma mark - 相册文件选取相关
 // 相册是否可用
 - (BOOL) isPhotoLibraryAvailable{
     return [UIImagePickerController isSourceTypeAvailable: UIImagePickerControllerSourceTypePhotoLibrary];
 }

 // 是否可以在相册中选择视频
 - (BOOL) canUserPickVideosFromPhotoLibrary{
     return [self cameraSupportsMedia:( NSString *)kUTTypeMovie sourceType:UIImagePickerControllerSourceTypePhotoLibrary];
 }

 // 是否可以在相册中选择视频
 - (BOOL) canUserPickPhotosFromPhotoLibrary{
     return [self cameraSupportsMedia:( NSString *)kUTTypeImage sourceType:UIImagePickerControllerSourceTypePhotoLibrary];
 }

三、用摄像头进行拍照和录像功能

我们将UIImagePickerController功能写在一个按钮的点击事件中

 #pragma mark - 拍照按钮事件

 - (void)ClickControlAction:(id)sender{
     // 判断有摄像头，并且支持拍照功能
     if ([self isCameraAvailable] && [self doesCameraSupportTakingPhotos]){
         // 初始化图片选择控制器
         UIImagePickerController *controller = [[UIImagePickerController alloc] init];
         [controller setSourceType:UIImagePickerControllerSourceTypeCamera];// 设置类型


         // 设置所支持的类型，设置只能拍照，或则只能录像，或者两者都可以
         NSString *requiredMediaType = ( NSString *)kUTTypeImage;
         NSString *requiredMediaType1 = ( NSString *)kUTTypeMovie;
         NSArray *arrMediaTypes=[NSArray arrayWithObjects:requiredMediaType, requiredMediaType1,nil];
         [controller setMediaTypes:arrMediaTypes];

         // 设置录制视频的质量
         [controller setVideoQuality:UIImagePickerControllerQualityTypeHigh];
         //设置最长摄像时间
         [controller setVideoMaximumDuration:10.f];


         [controller setAllowsEditing:YES];// 设置是否可以管理已经存在的图片或者视频
         [controller setDelegate:self];// 设置代理
         [self.navigationController presentModalViewController:controller animated:YES];
         [controller release];
     } else {
         NSLog(@"Camera is not available.");
     }
 }

具体解释一下：

1、setSourceType方法

通过设置setSourceType方法可以确定调用出来的UIImagePickerController所显示出来的界面

 typedef NS_ENUM(NSInteger, UIImagePickerControllerSourceType) {
     UIImagePickerControllerSourceTypePhotoLibrary,
     UIImagePickerControllerSourceTypeCamera,
     UIImagePickerControllerSourceTypeSavedPhotosAlbum
 };

分别表示：图片列表，摄像头，相机相册

2、setMediaTypes方法

 // 设置所支持的类型，设置只能拍照，或则只能录像，或者两者都可以
         NSString *requiredMediaType = ( NSString *)kUTTypeImage;
         NSString *requiredMediaType1 = ( NSString *)kUTTypeMovie;
         NSArray *arrMediaTypes=[NSArray arrayWithObjects:requiredMediaType, requiredMediaType1,nil];
         [controller setMediaTypes:arrMediaTypes];

3、关于UIImagePickerControllerDelegate协议

我们要对我们拍摄的照片和视频进行存储，那么就要实现UIImagePickerControllerDelegate协议的方法。

 #pragma mark - UIImagePickerControllerDelegate 代理方法


 // 保存图片后到相册后，调用的相关方法，查看是否保存成功
 - (void) imageWasSavedSuccessfully:(UIImage *)paramImage didFinishSavingWithError:(NSError *)paramError contextInfo:(voidvoid *)paramContextInfo{
     if (paramError == nil){
         NSLog(@"Image was saved successfully.");
     } else {
         NSLog(@"An error happened while saving the image.");
         NSLog(@"Error = %@", paramError);
     }
 }

 // 当得到照片或者视频后，调用该方法
 -(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info{
     NSLog(@"Picker returned successfully.");
     NSLog(@"%@", info);
     NSString *mediaType = [info objectForKey:UIImagePickerControllerMediaType];
     // 判断获取类型：图片
     if ([mediaType isEqualToString:( NSString *)kUTTypeImage]){
         UIImage *theImage = nil;
         // 判断，图片是否允许修改
         if ([picker allowsEditing]){
             //获取用户编辑之后的图像
             theImage = [info objectForKey:UIImagePickerControllerEditedImage];
         } else {
             // 照片的元数据参数
             theImage = [info objectForKey:UIImagePickerControllerOriginalImage];

         }

         // 保存图片到相册中
         SEL selectorToCall = @selector(imageWasSavedSuccessfully:didFinishSavingWithError:contextInfo:);
         UIImageWriteToSavedPhotosAlbum(theImage, self,selectorToCall, NULL);

     }else if ([mediaType isEqualToString:(NSString *)kUTTypeMovie]){
         // 判断获取类型：视频
         //获取视频文件的url
         NSURL* mediaURL = [info objectForKey:UIImagePickerControllerMediaURL];
         //创建ALAssetsLibrary对象并将视频保存到媒体库
         // Assets Library 框架包是提供了在应用程序中操作图片和视频的相关功能。相当于一个桥梁，链接了应用程序和多媒体文件。
         ALAssetsLibrary *assetsLibrary = [[ALAssetsLibrary alloc] init];
         // 将视频保存到相册中
         [assetsLibrary writeVideoAtPathToSavedPhotosAlbum:mediaURL
                                           completionBlock:^(NSURL *assetURL, NSError *error) {
                                               if (!error) {
                                                   NSLog(@"captured video saved with no error.");
                                               }else{
                                                   NSLog(@"error occured while saving the video:%@", error);
                                               }
                                           }];
         [assetsLibrary release];


     }


     [picker dismissModalViewControllerAnimated:YES];
 }


 // 当用户取消时，调用该方法
 - (void)imagePickerControllerDidCancel:(UIImagePickerController *)picker{

     [picker dismissModalViewControllerAnimated:YES];
 }

四、从相册获取图片和视频数据

1、我们将功能封装在一个按钮的点击事件中

 #pragma mark - 相册操作

 - (void)ClickShowPhotoAction:(id)sender{

     if ([self isPhotoLibraryAvailable]){
         UIImagePickerController *controller = [[UIImagePickerController alloc] init];
          [controller setSourceType:UIImagePickerControllerSourceTypePhotoLibrary];// 设置类型
         NSMutableArray *mediaTypes = [[NSMutableArray alloc] init];
         if ([self canUserPickPhotosFromPhotoLibrary]){
             [mediaTypes addObject:( NSString *)kUTTypeImage];
         }
         if ([self canUserPickVideosFromPhotoLibrary]){
             [mediaTypes addObject:( NSString *)kUTTypeMovie];
         }

         [controller setMediaTypes:mediaTypes];
         [controller setDelegate:self];// 设置代理
         [self.navigationController presentModalViewController:controller animated:YES];
         [controller release];
         [mediaTypes release];

     }
 }

2、关于UIImagePickerControllerDelegate协议

我们可以重用，在这里，就不用赘述了！

五、info信息

最后，需要说的是，UIImagePickerControllerDelegate协议中

-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info方法中的info值，会根据我们操作的类型不同，而产生了

不同的数据信息

1、当操作的为图片时

 {
     UIImagePickerControllerCropRect = "NSRect: {{0, 405}, {2448, 2449}}";
     UIImagePickerControllerEditedImage = "";
     UIImagePickerControllerMediaMetadata =     {
         DPIHeight = 72;
         DPIWidth = 72;
         Orientation = 6;
         "{Exif}" =         {
             ApertureValue = "2.526068811667588";
             BrightnessValue = "-0.0709875088566263";
             ColorSpace = 1;
             DateTimeDigitized = "2013:04:05 16:43:00";
             DateTimeOriginal = "2013:04:05 16:43:00";
             ExposureMode = 0;
             ExposureProgram = 2;
             ExposureTime = "0.05882352941176471";
             FNumber = "2.4";
             Flash = 24;
             FocalLenIn35mmFilm = 35;
             FocalLength = "4.28";
             ISOSpeedRatings =             (
                 400
             );
             MeteringMode = 5;
             PixelXDimension = 3264;
             PixelYDimension = 2448;
             SceneType = 1;
             SensingMethod = 2;
             Sharpness = 0;
             ShutterSpeedValue = "4.099543917546131";
             SubjectArea =             (
                 1631,
                 1223,
                 881,
                 881
             );
             WhiteBalance = 0;
         };
         "{TIFF}" =         {
             DateTime = "2013:04:05 16:43:00";
             Make = Apple;
             Model = "iPhone 4S";
             Software = "5.1.1";
             XResolution = 72;
             YResolution = 72;
         };
     };
     UIImagePickerControllerMediaType = "public.image";
     UIImagePickerControllerOriginalImage = "";
 }

2、当我们操作的为视频时

 {
     UIImagePickerControllerMediaType = "public.movie";
     UIImagePickerControllerMediaURL = "file://localhost/private/var/mobile/Applications/22A14825-DD7E-48E1-A1D5-2D85B82095B5/tmp/capture-T0x1363a0.tmp.etXfD4/capturedvideo.MOV";
 }

六、存储图片到app中和从app中读取图片

1、把选择的图片存储到app中

 NSString *imagePath = [[NSHomeDirectory() stringByAppendingPathComponent:@"Documents"] stringByAppendingPathComponent:@"image.png"];
 [UIImagePNGRepresentation(pickedImage) writeToFile:imagePath atomically:YES];

2、从app中读取存储的图片

 NSString *imagePath = [[NSHomeDirectory() stringByAppendingPathComponent:@"Documents"] stringByAppendingPathComponent:@"image.png"];
 UIImage *image = [[UIImage alloc] initWithContentsOfFile:imagePath];
 if (image) {
     self.imageView.image = image;
 }