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{
[imagePicker takePicture];
}
- (IBAction)press:(id)sender {
imagePicker = ［UIImagePickerController alloc] init];
imagePicker.delegate = self;
imagePicker.mediaTypes = [UIImagePickerController availableMediaTypesForSourceType: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];
[button addTarget:self action:@selector(pick) forControlEvents:UIControlEventTouchUpInside];
[view addSubview:button];
CGRect newFrame = CGRectMake(0.0,436,320,44);
view.frame = newFrame;
imagePicker.cameraOverlayView = view;
[self presentModalViewController:imagePicker animated:YES];
}
-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
if (［info objectForKey:UIImagePickerControllerMediaType] isEqualToString:(NSString*)kUTTypeImage]) {
UIImage* image = [info objectForKey:UIImagePickerControllerOriginalImage];
UIImageWriteToSavedPhotosAlbum(image, self, @selector(image:didFinishSavingWithError:contextInfo:), nil);