iOS摄像头和相册-UIImagePickerController-浅析

转载自：http://blog.sina.com.cn/s/blog_7b9d64af0101cfd9.html

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

 

1.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.");

}

}

 

 

解释：

 

2. 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

 

3.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];

 

 

4.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:(void *)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！

 

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：

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 = "";

}

 

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";

}

 

希望对你有所帮助！