[iOS]调用系统相机，相册，闪光灯

#import
//调用闪光灯调用框架
#import
 
@interface CameraViewController : UIViewController
{
    AVCaptureSession * _AVSession;//调用闪光灯的时候创建的类
}
 
@property(nonatomic,retain)AVCaptureSession * AVSession;
 
@end
在.m的- (void)viewDidLoad里建立4Button，Camera调用相机、Library调用图片库、flashlight打开闪光灯、close关闭闪光灯
//打开相机
-(void)addCarema
{
    //判断是否可以打开相机，模拟器此功能无法使用
    if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {
         
        UIImagePickerController * picker = [[UIImagePickerController alloc]init];
        picker.delegate = self;
        picker.allowsEditing = YES;  //是否可编辑
        //摄像头
        picker.sourceType = UIImagePickerControllerSourceTypeCamera;
        [self presentModalViewController:picker animated:YES];
        [picker release];
    }else{
        //如果没有提示用户
        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Error" message:@"你没有摄像头" delegate:nil cancelButtonTitle:@"Drat!" otherButtonTitles:nil];
        [alert show];
    }
}
打开相机后，然后需要调用UIImagePickerControllerDelegate里的方法，拍摄完成后执行的方法和点击Cancel之后执行的方法：
//拍摄完成后要执行的方法
-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
    //得到图片
    UIImage * image = [info objectForKey:UIImagePickerControllerOriginalImage];
    //图片存入相册
    UIImageWriteToSavedPhotosAlbum(image, nil, nil, nil);
    [self dismissModalViewControllerAnimated:YES];
     
}
//点击Cancel按钮后执行方法
-(void)imagePickerControllerDidCancel:(UIImagePickerController *)picker
{
    [self dismissModalViewControllerAnimated:YES];
}
调用相机照片和保存到图片库已经完成。
接着介绍打开照片库：
-(void)openPicLibrary
{
    //相册是可以用模拟器打开的
    if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypePhotoLibrary]) {
        UIImagePickerController * picker = [[UIImagePickerController alloc]init];
        picker.delegate = self;
        picker.allowsEditing = YES;//是否可以编辑
 
        //打开相册选择照片
        picker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
        [self presentModalViewController:picker  animated:YES];
        [picker release];
    }else{
        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Error" message:@"你没有摄像头" delegate:nil cancelButtonTitle:@"Drat!" otherButtonTitles:nil];
        [alert show];
    }
     
}
 
//选中图片进入的代理方法
-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingImage:(UIImage *)image editingInfo:(NSDictionary *)editingInfo
{
    [self dismissModalViewControllerAnimated:YES];
}
调用闪光灯的代码，由于我也不是很理解，所以没法加注释，但是已经亲测可用，但是调闪光灯时有一个算是bug吧，闪光灯会闲一下，然后再一直亮
-(void)openFlashlight
{
    AVCaptureDevice * device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
    if (device.torchMode == AVCaptureTorchModeOff) {
        //Create an AV session
        AVCaptureSession * session = [[AVCaptureSession alloc]init];
         
        // Create device input and add to current session
        AVCaptureDeviceInput * input = [AVCaptureDeviceInput deviceInputWithDevice:device error:nil];
        [session addInput:input];
         
        // Create video output and add to current session
        AVCaptureVideoDataOutput * output = [[AVCaptureVideoDataOutput alloc]init];
        [session addOutput:output];
         
        // Start session configuration
        [session beginConfiguration];
        [device lockForConfiguration:nil];
         
        // Set torch to on
        [device setTorchMode:AVCaptureTorchModeOn];
         
        [device unlockForConfiguration];
        [session commitConfiguration];
         
        // Start the session
        [session startRunning];
         
        // Keep the session around
        [self setAVSession:self.AVSession];
         
        [output release];
    }
}
 
-(void)closeFlashlight
{
    [self.AVSession stopRunning];
    [self.AVSession release];
}