iOS巔峯之調用系統相機和打開閃光燈

IOS有兩種的拍照和視頻的方式：1.直接使用UIImagePickerController，這個類提供了一個簡單便捷的拍照與選擇圖片庫裏圖片的功能。2.另一種是通過AVFoundation.framework框架完全自定義拍照的界面和選擇圖片庫界面。我只做了第一種，就先給大家介紹第一種做法：
一、首先調用接口前，我們需要先判斷當前設備是否支持UIImagePickerController，用isSourceTypeAvailable:來判斷是否可用
二、查看符合的媒體類型，這個時候我們調用availableMediaTypeForSourceType：判斷
在調用UIImagePickerController時我們需要加入他的兩個代理方法：
UINavigationControllerDelegate和UIImagePickerControllerDelegate，在調用攝像頭的時候還可以調閃光燈，一會代碼裏有。

要調用閃光燈需要先建一個AVCaptureSession類的實例對象:

#import <UIKit/UIKit.h>
//調用閃光燈調用框架
#import <AVFoundation/AVFoundation.h>

@interface CameraViewController : UIViewController<UINavigationControllerDelegate, UIImagePickerControllerDelegate>
{
    AVCaptureSession * _AVSession;//調用閃光燈的時候創建的類
}

@property(nonatomic,retain)AVCaptureSession * AVSession;

@end

在.m的- (void)viewDidLoad裏建立4Button，Camera調用相機、Library調用圖片庫、flashlight打開閃光燈、close關閉閃光燈

//打開相機
-(void)addCarema
{
    //判斷是否可以打開相機，模擬器此功能無法使用
    if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {

        UIImagePickerController * picker = [[UIImagePickerController alloc]init];
        picker.delegate = self;
        picker.allowsEditing = YES;  //是否可編輯
        //攝像頭
        picker.sourceType = UIImagePickerControllerSourceTypeCamera;
        [self presentModalViewController:picker animated:YES];
        [picker release];
    }else{
        //如果沒有提示用戶
        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Error" message:@"你沒有攝像頭" delegate:nil cancelButtonTitle:@"Drat!" otherButtonTitles:nil];
        [alert show];
    }
}

打開相機後，然後需要調用UIImagePickerControllerDelegate裏的方法，拍攝完成後執行的方法和點擊Cancel之後執行的方法：

//拍攝完成後要執行的方法
-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
    //得到圖片
    UIImage * image = [info objectForKey:UIImagePickerControllerOriginalImage];
    //圖片存入相冊
    UIImageWriteToSavedPhotosAlbum(image, nil, nil, nil);
    [self dismissModalViewControllerAnimated:YES];

}
//點擊Cancel按鈕後執行方法
-(void)imagePickerControllerDidCancel:(UIImagePickerController *)picker
{
    [self dismissModalViewControllerAnimated:YES];
}

調用相機照片和保存到圖片庫已經完成。
接着介紹打開照片庫：

-(void)openPicLibrary
{
    //相冊是可以用模擬器打開的
    if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypePhotoLibrary]) {
        UIImagePickerController * picker = [[UIImagePickerController alloc]init];
        picker.delegate = self;
        picker.allowsEditing = YES;//是否可以編輯

        //打開相冊選擇照片
        picker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
        [self presentModalViewController:picker  animated:YES];
        [picker release];
    }else{
        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Error" message:@"你沒有攝像頭" delegate:nil cancelButtonTitle:@"Drat!" otherButtonTitles:nil];
        [alert show];
    }

}

//選中圖片進入的代理方法
-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingImage:(UIImage *)image editingInfo:(NSDictionary *)editingInfo
{
    [self dismissModalViewControllerAnimated:YES];
}

調用閃光燈的代碼

-(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];
}