iOS摄像头和相册-UIImagePickerController-浅析

转自：http://www.2cto.com/kf/201406/312257.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！