UIImagePickerController学习

UIImagePickerController概述：
UIImagePickerController 类是获取选择图片和视频的用户接口。我们可以用这个controller选择我们所需要的图片和视频。对于这个类来说比较特殊，我们不能够任意定制，也不可以继承生成子类。
我们在用UIImagePickerController类的时候，只需要调用用代码实现其在什么位置显示和开始，当然我们之后可以选择所需的图片和影片，或者也可以不选择点击取消即可。
但是在我们调用接口之前，我们需要确认：
一：当前设备是否支持使用UIImagePickerController，这个时候我们需要调用isSourceTypeAvailable:方法判断。
二：查看符合的媒体类型（图片或者视频），这个时候我们调用availableMediaTypesForSourceType: 方法判断。
同时使用UIImagePickerController时，我们需要UIImagePickerControllerDelegate协议代理实现一些特定时间特定的动作。在调用摄像头的时候我们可以选择使用闪光灯，但是默认条件下对视频有10分钟的限制，需要用videoMaximumDuration属性更改默认时间，
三：之后我们设定界面媒体的属性  
1：sourceType  //从哪选取媒体
enum {
UIImagePickerControllerSourceTypePhotoLibrary,
UIImagePickerControllerSourceTypeCamera,
UIImagePickerControllerSourceTypeSavedPhotosAlbum
};
typedef NSUInteger UIImagePickerControllerSourceType;
2:   mediaTypes
mediaTypes用来确定再picker里显示那些类型的多媒体文件，图片？视频？
+ (NSArray *)availableMediaTypesForSourceType:(UIImagePickerControllerSourceType)sourceType
一共有三个可选的代理方法UIImagePickerControllerDelegate 
– imagePickerController:didFinishPickingMediaWithInfo:  
– imagePickerControllerDidCancel:  
– imagePickerController:didFinishPickingImage:editingInfo: 
-(void)pick{
[imagePickertakePicture];
}
-(IBAction)press:(id)sender {
imagePicker= ［UIImagePickerController alloc] init];
imagePicker.delegate= self;
imagePicker.mediaTypes= [UIImagePickerControlleravailableMediaTypesForSourceType:UIImagePickerControllerSourceTypeCamera];
imagePicker.sourceType= UIImagePickerControllerSourceTypeCamera;
imagePicker.showsCameraControls= NO;

UIView*view = ［UIView alloc] initWithFrame:CGRectMake(0, 0, 320,44)];
view.backgroundColor= [UIColor redColor];
UIButton*button = ［UIButton alloc] initWithFrame:CGRectMake(0, 0, 40,40)];
button.backgroundColor= [UIColor blueColor];
[buttonaddTarget:self action:@selector(pick)forControlEvents:UIControlEventTouchUpInside];
[viewaddSubview:button];

CGRectnewFrame = CGRectMake(0.0,436,320,44);
view.frame= newFrame;
imagePicker.cameraOverlayView= view;
[selfpresentModalViewController:imagePickeranimated:YES];
}
-(void)imagePickerController:(UIImagePickerController*)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {
if(［info objectForKey:UIImagePickerControllerMediaType]isEqualToString:(NSString*)kUTTypeImage]) {
UIImage*image = [infoobjectForKey:UIImagePickerControllerOriginalImage];
UIImageWriteToSavedPhotosAlbum(image,self, @selector(image:didFinishSavingWithError:contextInfo:),nil);
} elseif (［info objectForKey:UIImagePickerControllerMediaType]isEqualToString:(NSString*)kUTTypeMovie]) {
NSString*path = ［info objectForKey:UIImagePickerControllerMediaURL]path];
   UISaveVideoAtPathToSavedPhotosAlbum(path,self, @selector(video:didFinishSavingWithError:contextInfo:),nil);
}
[pickerdismissModalViewControllerAnimated:YES];
}
-(void)imagePickerControllerDidCancel:(UIImagePickerController*)picker {
[pickerdismissModalViewControllerAnimated:YES];
}

UIImagePickerController
－－ the only sanctioned way to get videos/movies or images/pictures on supported devices

用UIImagePickerController选择、显示图片或视频，主要注意UIImagePickerController几个属性的设置
一：UI 显示样式，显示的格式确定
1：sourceType
@property(nonatomic) UIImagePickerControllerSourceType sourceType
enum {
UIImagePickerControllerSourceTypePhotoLibrary,
UIImagePickerControllerSourceTypeCamera,
UIImagePickerControllerSourceTypeSavedPhotosAlbum
};
typedef NSUInteger UIImagePickerControllerSourceType;
sourceType用来确定用户界面显示的样式：
共三种格式（模拟器上的效果图）
UIImagePickerControllerSourceTypePhotoLibrary,
UIImagePickerControllerSourceTypeCamera,

UIImagePickerControllerSourceTypeSavedPhotosAlbum

为了区分是否支持视频格式，一般要用到下面这个函数，以便确定mediaTypes。
+ (BOOL)isSourceTypeAvailable:(UIImagePickerControllerSourceType)sourceType
2:   mediaTypes
@property(nonatomic,copy) NSArray *mediaTypes
mediaTypes用来确定再picker里显示那些类型的多媒体文件，图片？视频？
+ (NSArray *)availableMediaTypesForSourceType:(UIImagePickerControllerSourceType)sourceType
二：选取动作处理
UIImagePickerControllerDelegate 
通过代理来完成用户在选中图片，或者choose视频时的处理方式：
共有三个可选的代理方法
– imagePickerController:didFinishPickingMediaWithInfo:  
– imagePickerControllerDidCancel:  
– imagePickerController:didFinishPickingImage:editingInfo:   Deprecated in iPhone OS 3.0
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
info中包括选取的照片，视频的主要信息
NSString *const UIImagePickerControllerMediaType;         选取的类型 public.image  public.movie
NSString *const UIImagePickerControllerOriginalImage;    修改前的UIImage object.
NSString *const UIImagePickerControllerEditedImage;      修改后的UIImage object.
NSString *const UIImagePickerControllerCropRect;           原始图片的尺寸NSValue object containing a CGRect data type
NSString *const UIImagePickerControllerMediaURL;          视频在文件系统中 的 NSURL地址
保存视频主要时通过获取其NSURL 然后转换成NSData
实例代码如下：
- (void) pickImage: (id) sender
{
UIImagePickerController *ipc = [[UIImagePickerController alloc] init];
        if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypePhotoLibrary]){
     ipc.sourceType =  UIImagePickerControllerSourceTypePhotoLibrary;
      ipc.mediaTypes =[UIImagePickerController availableMediaTypesForSourceType:ipc.sourceType];   
        } 
ipc.delegate = self;
ipc.allowsImageEditing = NO;
[self presentModalViewController:ipc animated:YES]; 
}
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
NSString *mediaType = [info objectForKey:UIImagePickerControllerMediaType];
if ([mediaType isEqualToString:@"public.image"]){
// UIImage *selectedImage = [info objectForKey:UIImagePickerControllerOriginalImage];
UIImage *image = [info objectForKey:@"UIImagePickerControllerOriginalImage"];
    NSLog(@"found an image");
[UIImageJPEGRepresentation(image, 1.0f) writeToFile:[self findUniqueSavePath] atomically:YES];
    SETIMAGE(image);
CFShow([[NSFileManager defaultManager] directoryContentsAtPath:[NSHomeDirectory() stringByAppendingString:@"/Documents"]]);
}
else if ([mediaType isEqualToString:@"public.movie"]){
NSURL *videoURL = [info objectForKey:UIImagePickerControllerMediaURL];
NSLog(@"found a video");
        NSData *webData = [NSData dataWithContentsOfURL:videoURL];
//NSData *video = [[NSString alloc] initWithContentsOfURL:videoURL];
[webData writeToFile:[self findUniqueMoviePath] atomically:YES];
CFShow([[NSFileManager defaultManager] directoryContentsAtPath:[NSHomeDirectory() stringByAppendingString:@"/Documents"]]);
// NSLog(videoURL);
}
[picker dismissModalViewControllerAnimated:YES];
}