iOS摄像头和相册-UIImagePickerController-浅析
本文转载自：http://blog.sina.com.cn/s/blog_7b9d64af0101cfd9.html
在原文的基础上，增加了存储图片到app和从app存储中读取图片。
摘要：
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:(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！
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;
}
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