iOS摄像头和相册-UIImagePickerController-浅析

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！Soeasy！！！

#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 *)paramMediaTypesourceType:(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
[UIImagePickerControllerisSourceTypeAvailable:UIImagePickerControllerSourceTypePhotoLibrary];
}

//是否可以在相册中选择视频
-(BOOL)canUserPickVideosFromPhotoLibrary{

return
[selfcameraSupportsMedia:(
NSString *)kUTTypeMovie
sourceType:UIImagePickerControllerSourceTypePhotoLibrary];
}

//是否可以在相册中选择视频
-(BOOL)canUserPickPhotosFromPhotoLibrary{

return
[selfcameraSupportsMedia:(
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
([selfisCameraAvailable] &&[selfdoesCameraSupportTakingPhotos]){
//
初始化图片选择控制器
UIImagePickerController
*controller =[[UIImagePickerController
alloc]init];
[controllersetSourceType: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
[controllersetVideoQuality: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.navigationControllerpresentModalViewController: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 *)paramImagedidFinishSavingWithError:(NSError
*)paramErrorcontextInfo:(void*)paramContextInfo{

if (paramError == nil){

NSLog(@"Image was savedsuccessfully.");
}
else {

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

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

//当得到照片或者视频后，调用该方法
-(void)imagePickerController:(UIImagePickerController *)pickerdidFinishPickingMediaWithInfo:(NSDictionary
*)info{

NSLog(@"Picker returnedsuccessfully.");

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 ([pickerallowsEditing]){

//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

SELselectorToCall =
@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

// AssetsLibrary 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

[assetsLibrarywriteVideoAtPathToSavedPhotosAlbum:mediaURL
completionBlock:^(NSURL
*assetURL, NSError *error) {

if (!error) {

NSLog(@"captured video saved with noerror.");
}else{

NSLog(@"erroroccured 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 ([selfcanUserPickPhotosFromPhotoLibrary]){
[mediaTypes
addObject:(NSString *)kUTTypeImage];
}

if ([selfcanUserPickVideosFromPhotoLibrary]){
[mediaTypes
addObject:(NSString *)kUTTypeMovie];
}

[controller
setMediaTypes:mediaTypes];
[controller
setDelegate:self];//
设置代理

[self.navigationControllerpresentModalViewController: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 *)pickerdidFinishPickingMediaWithInfo:(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！