UIImagePickerController 淺析

在一些應用中，我們需要用到iOS設備的攝像頭進行拍照，視頻。並且從相冊中選取我們需要的圖片或者視頻。

關於iOS攝像頭和相冊的應用，可以使用UIImagePickerController類來完成控制。

關於UIImagePickerController的相關知識，

如下：

iOS的一些設備上都安裝了攝像頭。現在絕大多數都有了。

在編程中，我們是用相應的東西來進行照相，錄像等功能。

一、UIImagePickerController類

UIImagePickerController 這個類可以爲大家提供照相的功能,以及圖片,視頻瀏覽的功能。 

二、檢查硬件是否安裝有攝像頭或者允許操作相冊

這些公共的方法，我們也許會用到，我就貼了！So easy！！！

#pragma mark - 攝像頭和相冊相關的公共類

// 判斷設備是否有攝像頭

- (BOOL) isCameraAvailable{

    return [UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera];

}

// 前面的攝像頭是否可用

- (BOOL) isFrontCameraAvailable{

    return [UIImagePickerControllerisCameraDeviceAvailable:UIImagePickerControllerCameraDeviceFront];

}

// 後面的攝像頭是否可用

- (BOOL) isRearCameraAvailable{

    return [UIImagePickerControllerisCameraDeviceAvailable:UIImagePickerControllerCameraDeviceRear];

}

// 判斷是否支持某種多媒體類型：拍照，視頻

- (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;

}

// 檢查攝像頭是否支持錄像

- (BOOL) doesCameraSupportShootingVideos{

    return [self cameraSupportsMedia:( NSString *)kUTTypeMoviesourceType:UIImagePickerControllerSourceTypeCamera];

}

// 檢查攝像頭是否支持拍照

- (BOOL) doesCameraSupportTakingPhotos{

    return [self cameraSupportsMedia:( NSString *)kUTTypeImagesourceType:UIImagePickerControllerSourceTypeCamera];

}

#pragma mark - 相冊文件選取相關

// 相冊是否可用

- (BOOL) isPhotoLibraryAvailable{

    return [UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypePhotoLibrary];

}

// 是否可以在相冊中選擇視頻

- (BOOL) canUserPickVideosFromPhotoLibrary{

    return [self cameraSupportsMedia:( NSString *)kUTTypeMoviesourceType:UIImagePickerControllerSourceTypePhotoLibrary];

}

// 是否可以在相冊中選擇視頻

- (BOOL) canUserPickPhotosFromPhotoLibrary{

    return [self cameraSupportsMedia:( NSString *)kUTTypeImagesourceType:UIImagePickerControllerSourceTypePhotoLibrary];

}

三、用攝像頭進行拍照和錄像功能

1.我們將UIImagePickerController功能寫在一個按鈕的點擊事件中：

 

#pragma mark - 拍照按鈕事件

- (void)ClickControlAction:(id)sender{

    // 判斷有攝像頭，並且支持拍照功能

    if ([self isCameraAvailable] && [self doesCameraSupportTakingPhotos]){

        // 初始化圖片選擇控制器

        UIImagePickerController *controller = [[UIImagePickerController alloc] init];

        [controller setSourceType:UIImagePickerControllerSourceTypeCamera];// 設置類型

        

        // 設置所支持的類型，設置只能拍照，或則只能錄像，或者兩者都可以

        NSString *requiredMediaType = ( NSString *)kUTTypeImage;

        NSString *requiredMediaType1 = ( NSString *)kUTTypeMovie;

        NSArray *arrMediaTypes=[NSArray arrayWithObjects:requiredMediaType, requiredMediaType1,nil];

        [controller setMediaTypes:arrMediaTypes];

        

        // 設置錄製視頻的質量

        [controller setVideoQuality:UIImagePickerControllerQualityTypeHigh];

        //設置最長攝像時間

        [controller setVideoMaximumDuration:10.f];

        

        [controller setAllowsEditing:YES];// 設置是否可以管理已經存在的圖片或者視頻

        [controller setDelegate:self];// 設置代理

        [self.navigationController presentModalViewController:controller animated:YES];

        [controller release];

    } else {

        NSLog(@"Camera is not available.");

    }

}

解釋：

2. setSourceType方法

通過設置setSourceType方法可以確定調用出來的UIImagePickerController所顯示出來的界面

typedef NS_ENUM(NSInteger, UIImagePickerControllerSourceType) {

    UIImagePickerControllerSourceTypePhotoLibrary,

    UIImagePickerControllerSourceTypeCamera,

    UIImagePickerControllerSourceTypeSavedPhotosAlbum

};

分別表示：圖片列表，攝像頭，相機相冊

3.setMediaTypes方法

// 設置所支持的類型，設置只能拍照，或則只能錄像，或者兩者都可以

        NSString *requiredMediaType = ( NSString *)kUTTypeImage;

        NSString *requiredMediaType1 = ( NSString *)kUTTypeMovie;

        NSArray *arrMediaTypes=[NSArray arrayWithObjects:requiredMediaType, requiredMediaType1,nil];

        [controller setMediaTypes:arrMediaTypes];

4.關於UIImagePickerControllerDelegate協議

我們要對我們拍攝的照片和視頻進行存儲，那麼就要實現UIImagePickerControllerDelegate協議的方法。

#pragma mark - UIImagePickerControllerDelegate 代理方法

// 保存圖片後到相冊後，調用的相關方法，查看是否保存成功

- (void) imageWasSavedSuccessfully:(UIImage *)paramImage didFinishSavingWithError:(NSError *)paramError contextInfo:(void *)paramContextInfo{

    if (paramError == nil){

        NSLog(@"Image was saved successfully.");

    } else {

        NSLog(@"An error happened while saving the image.");

        NSLog(@"Error = %@", paramError);

    }

}

// 當得到照片或者視頻後，調用該方法

-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info{

    NSLog(@"Picker returned successfully.");

    NSLog(@"%@", info);

    NSString *mediaType = [info objectForKey:UIImagePickerControllerMediaType];

    // 判斷獲取類型：圖片

    if ([mediaType isEqualToString:( NSString *)kUTTypeImage]){

        UIImage *theImage = nil;

        // 判斷，圖片是否允許修改

        if ([picker allowsEditing]){

            //獲取用戶編輯之後的圖像

            theImage = [info objectForKey:UIImagePickerControllerEditedImage];

        } else {

            // 照片的元數據參數

            theImage = [info objectForKey:UIImagePickerControllerOriginalImage];

            

        }

        

        // 保存圖片到相冊中

        SEL selectorToCall = @selector(imageWasSavedSuccessfully:didFinishSavingWithError:contextInfo:);

        UIImageWriteToSavedPhotosAlbum(theImage, self,selectorToCall, NULL);

        

    }else if ([mediaType isEqualToString:(NSString *)kUTTypeMovie]){

        // 判斷獲取類型：視頻

        //獲取視頻文件的url

        NSURL* mediaURL = [info objectForKey:UIImagePickerControllerMediaURL];

        //創建ALAssetsLibrary對象並將視頻保存到媒體庫

        // Assets Library 框架包是提供了在應用程序中操作圖片和視頻的相關功能。相當於一個橋樑，鏈接了應用程序和多媒體文件。

        ALAssetsLibrary *assetsLibrary = [[ALAssetsLibrary alloc] init];

        // 將視頻保存到相冊中

        [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];

}

// 當用戶取消時，調用該方法

- (void)imagePickerControllerDidCancel:(UIImagePickerController *)picker{

    

    [picker dismissModalViewControllerAnimated:YES];

}

四、從相冊獲取圖片和視頻數據

1.我們將功能封裝在一個按鈕的點擊事件中

#pragma mark - 相冊操作

- (void)ClickShowPhotoAction:(id)sender{

    

    if ([self isPhotoLibraryAvailable]){

        UIImagePickerController *controller = [[UIImagePickerController alloc]init];

         [controller setSourceType:UIImagePickerControllerSourceTypePhotoLibrary];// 設置類型

        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];// 設置代理

        [self.navigationController presentModalViewController:controlleranimated:YES];

        [controller release];

        [mediaTypes release];

        

    }

}

2.關於UIImagePickerControllerDelegate協議，我們可以重用。

在這裏，就不用贅述了！

最後，需要說的是，UIImagePickerControllerDelegate協議中

-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info方法，中的info值，會根據我們操作的類型不同，而產生了不同的數據信息：

當操作的爲圖片時：：

 

{

    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 = "";

}

當我們操作的爲視頻時：

{

    UIImagePickerControllerMediaType = "public.movie";

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

}

希望對你有所幫助！

    

//    NSData * imgData  = nil;

//    if (gotImg) {

//        if (UIImagePNGRepresentation(gotImg)) {

//            imgData = UIImagePNGRepresentation(gotImg);

//            

//        }else{

//            imgData = UIImageJPEGRepresentation(gotImg, 1.0);

//        }

//    }

//    

//    

//    

//    

//    ALAssetsLibrary *assetsLibrary = [[ALAssetsLibrary alloc] init];

//    // 將圖片保存到相冊中

//    [assetsLibrary writeImageDataToSavedPhotosAlbum:imgData metadata:metaData completionBlock:^(NSURL *assetURL, NSError *error) {

//        

//        if (assetURL) {

//            

//            NSLog(@"保存圖片到相冊%@",assetURL);

//            

//        }else{

//        

//        }

//        

//        NSLog(@"%@",error);

//    }];