引言

UIImagePickerController確實非常強大，但是雨MPMoviePlayerController類似，由于它的高度封裝性，要進行某些自定義工作就比較復雜了。例如要做出一款類似于美顏相機的拍照界面就比較難以實現了，此時就可以考慮使用AVFoundation來實現。AVFoundation中提供了很多現成的播放器和錄音機，但是事實上他還有更加底層的內容可以供開發者使用。因為AVFoundation中抽了很多和底層輸入，輸出設備打交道的類，依靠這些類開發人員面對的不再是封裝好的音頻播放器AVAudioPlayer、錄音機（AVAudioRecorder）、視頻（包括音頻）播放器AVPlayer，而是輸入設備（例如麥克風、攝像頭）、輸出設備（圖片、視頻）等。首先了解一下使用AVFoundation做拍照和視頻錄制開發用到的相關類：

• AVCaptureSession：媒體（音、視頻）捕獲會話，負責把捕獲的音視頻數據輸出到輸出設備中。一個AVCaptureSession可以有多個輸入輸出：如圖：

AVCaptureSession可以有多個輸入輸出

• AVCaptureDevice：輸入設備，包括麥克風、攝像頭，通過該對象可以設置物理設備的一些屬性（例如相機聚焦、白平衡等）。
• AVCaptureDeviceInput：設備輸入數據管理對象，可以根據AVCaptureDevice創建對應的AVCaptureDeviceInput對象，該對象將會被添加到AVCaptureSession中管理。
• AVCaptureOutput：輸出數據管理對象，用于接收各類輸出數據，通常使用對應的子類AVCaptureAudioDataOutput、AVCaptureStillImageOutput、AVCaptureVideoDataOutput、AVCaptureFileOutput，該對象將會被添加到AVCaptureSession中管理。注意：前面幾個對象的輸出數據都是NSData類型，而AVCaptureFileOutput代表數據以文件形式輸出，類似的，AVCcaptureFileOutput也不會直接創建使用，通常會使用其子類：AVCaptureAudioFileOutput、AVCaptureMovieFileOutput。當把一個輸入或者輸出添加到AVCaptureSession之后AVCaptureSession就會在所有相符的輸入、輸出設備之間建立連接（AVCaptionConnection）：

輸入、輸出設備之間建立連接

• AVCaptureVideoPreviewLayer：相機拍攝預覽圖層，是CALayer的子類，使用該對象可以實時查看拍照或視頻錄制效果，創建該對象需要指定對應的AVCaptureSession對象。

使用AVFoundation拍照和錄制視頻的一般步驟如下：

• 創建AVCaptureSession對象。
• 使用AVCaptureDevice的靜態方法獲得需要使用的設備，例如拍照和錄像就需要獲得攝像頭設備，錄音就要獲得麥克風設備。
• 利用輸入設備AVCaptureDevice初始化AVCaptureDeviceInput對象。
• 初始化輸出數據管理對象，如果要拍照就初始化AVCaptureStillImageOutput對象；如果拍攝視頻就初始化AVCaptureMovieFileOutput對象。
• 將數據輸入對象AVCaptureDeviceInput、數據輸出對象AVCaptureOutput添加到媒體會話管理對象AVCaptureSession中。
• 創建視頻預覽圖層AVCaptureVideoPreviewLayer并指定媒體會話，添加圖層到顯示容器中，調用AVCaptureSession的startRuning方法開始捕獲。
• 將捕獲的音頻或視頻數據輸出到指定文件。

下面看一下如何使用AVFoundation實現一個拍照程序，在這個程序中將實現攝像頭預覽、切換前后攝像頭、閃光燈設置、對焦、拍照保存等功能。應用大致效果如下：

#import "AVCostomAVViewController.h"
#import <AVFoundation/AVFoundation.h>
#import <AssetsLibrary/AssetsLibrary.h>


#define ScreenWith     [UIScreen mainScreen].bounds.size.width
#define ScreenHeight   [UIScreen mainScreen].bounds.size.height

typedef void(^PropertyChangeBlock) (AVCaptureDevice * captureDevice);

@interface AVCostomAVViewController ()<AVCaptureFileOutputRecordingDelegate>//視頻文件輸出代理
//負責輸入和輸出設備之間的數據傳輸
@property (nonatomic, strong) AVCaptureSession * captureSession;
//負責從AVCaptureDevice獲得輸入數據
@property (nonatomic, strong) AVCaptureDeviceInput * captureDeviceInput;
//照片輸出流
@property (nonatomic, strong) AVCaptureStillImageOutput * captureStillImageOutput;
//視頻輸出流
@property (nonatomic, strong) AVCaptureMovieFileOutput * captureMovieFileOutPut;
@property (assign,nonatomic) UIBackgroundTaskIdentifier backgroundTaskIdentifier;//后臺任務標識

//相機拍攝預覽圖層
@property (nonatomic, strong) AVCaptureVideoPreviewLayer * captureVideoPreviewLayer;
@property (nonatomic, strong) UIView * contentView;
//拍照按鈕
@property (nonatomic, strong) UIButton * takeButton;
//視頻錄制按鈕
@property (nonatomic, strong) UIButton * videoButton;
//自動閃光燈按鈕
@property (nonatomic, strong) UIButton * flashAutoButton;
//打開閃光燈按鈕
@property (nonatomic, strong) UIButton * flashOnButton;
//關閉閃光燈按鈕
@property (nonatomic, strong) UIButton * flashOffButton;
//切換前后攝像頭
@property (nonatomic, strong) UIButton * exchangeCamera;
//聚焦光標
@property (nonatomic, strong) UIImageView * focusCursor;

@end

@implementation AVCostomAVViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    self.view.backgroundColor = [UIColor whiteColor];
    self.title = @"自定義拍照和視頻錄制控件";
    
    [self setupUI];
    
    [self initCamera];
    
    [self.captureSession startRunning];

}

- (void)viewDidAppear:(BOOL)animated{
    [super viewDidAppear:animated];
}

- (void)viewDidDisappear:(BOOL)animated{
    [super viewDidDisappear:animated];
    [self.captureSession stopRunning];
}

- (void)dealloc{
    [[NSNotificationCenter defaultCenter] removeObserver:self];
}

#pragma mark - 攝像頭初始化
- (void)initCamera{
    //初始化會話
    _captureSession = [[AVCaptureSession alloc] init];
    //設置分辨率
    if ([_captureSession canSetSessionPreset:AVCaptureSessionPreset1280x720]) {
        _captureSession.sessionPreset=AVCaptureSessionPreset1280x720;
    }
    //獲得輸入設備
    AVCaptureDevice * captureDevice = [self getCameraDeviceWithPosition:AVCaptureDevicePositionBack];
    if (!captureDevice) {
        NSLog(@"取得后置攝像頭時出現問題。");
        return;
    }
    
    NSError * error = nil;
    
    //添加一個音頻輸入設備
    AVCaptureDevice * audioCaptureDevice = [[AVCaptureDevice devicesWithMediaType:AVMediaTypeAudio] firstObject];
    AVCaptureDeviceInput * audioCaptureDeviceInput = [[AVCaptureDeviceInput alloc] initWithDevice:audioCaptureDevice error:&error];
    if (error) {
        NSLog(@"獲得設備輸入對象時出錯，錯誤原因：%@",error.localizedDescription);
        return;
    }
    
    _captureMovieFileOutPut = [[AVCaptureMovieFileOutput alloc] init];
    
    //根據輸入設備初始化設備輸入對象，用于獲得輸入數據
    _captureDeviceInput = [[AVCaptureDeviceInput alloc]initWithDevice:captureDevice error:&error];
    if (error) {
        NSLog(@"取得設備輸入對象時出錯，錯誤原因：%@",error.localizedDescription);
        return;
    }
    //初始化設備輸出對象，用于獲得輸出數據
    _captureStillImageOutput = [[AVCaptureStillImageOutput alloc] init];
    NSDictionary * outputSettings = @{AVVideoCodecKey:AVVideoCodecJPEG};
    //輸出設置
    [_captureStillImageOutput setOutputSettings:outputSettings];
    
    //將設備輸入添加到會話中
    if ([_captureSession canAddInput:_captureDeviceInput]) {
        [_captureSession addInput:_captureDeviceInput];
        [_captureSession addInput:audioCaptureDeviceInput];
        AVCaptureConnection * captureConnection = [_captureMovieFileOutPut connectionWithMediaType:AVMediaTypeVideo];
        ;
        if ([captureConnection isVideoStabilizationSupported]) {
            captureConnection.preferredVideoStabilizationMode= AVCaptureVideoStabilizationModeAuto;
        }
    }
    
    //將設輸出添加到會話中
    if ([_captureSession canAddOutput:_captureStillImageOutput]) {
        [_captureSession addOutput:_captureStillImageOutput];
    }
    
    if ([_captureSession canAddOutput:_captureMovieFileOutPut]) {
        [_captureSession addOutput:_captureMovieFileOutPut];
    }
    
    //創建視頻預覽層，用于實時展示攝像頭狀態
    _captureVideoPreviewLayer = [[AVCaptureVideoPreviewLayer alloc]initWithSession:self.captureSession];
    
    CALayer * layer = self.contentView.layer;
    layer.masksToBounds = YES;
    
    _captureVideoPreviewLayer.frame = layer.bounds;
    //填充模式
    _captureVideoPreviewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
    
    //將視頻預覽層添加到界面中
    [layer insertSublayer:_captureVideoPreviewLayer below:self.focusCursor.layer];
    
    [self addNotificationToCaptureDevice:captureDevice];
    [self addGenstureRecognizer];
    [self setFlashModeButtonStatus];
}

#pragma mark - 視頻輸出代理
-(void)captureOutput:(AVCaptureFileOutput *)captureOutput didStartRecordingToOutputFileAtURL:(NSURL *)fileURL fromConnections:(NSArray *)connections{
    NSLog(@"開始錄制...");
}
-(void)captureOutput:(AVCaptureFileOutput *)captureOutput didFinishRecordingToOutputFileAtURL:(NSURL *)outputFileURL fromConnections:(NSArray *)connections error:(NSError *)error{
    NSLog(@"視頻錄制完成.");
    //視頻錄入完成之后在后臺將視頻存儲到相簿
  //  self.enableRotation=YES;
    UIBackgroundTaskIdentifier lastBackgroundTaskIdentifier=self.backgroundTaskIdentifier;
    self.backgroundTaskIdentifier=UIBackgroundTaskInvalid;
    ALAssetsLibrary *assetsLibrary=[[ALAssetsLibrary alloc]init];
    [assetsLibrary writeVideoAtPathToSavedPhotosAlbum:outputFileURL completionBlock:^(NSURL *assetURL, NSError *error) {
        if (error) {
            NSLog(@"保存視頻到相簿過程中發生錯誤，錯誤信息：%@",error.localizedDescription);
        }
        if (lastBackgroundTaskIdentifier!=UIBackgroundTaskInvalid) {
            [[UIApplication sharedApplication] endBackgroundTask:lastBackgroundTaskIdentifier];
        }
        NSLog(@"成功保存視頻到相簿.");
    }];
    
}

#pragma mark - 攝像頭相關
//  給輸入設備添加通知
-(void)addNotificationToCaptureDevice:(AVCaptureDevice *)captureDevice{
    //注意添加區域改變捕獲通知必須首先設置設備允許捕獲
    [self changeDeviceProperty:^(AVCaptureDevice *captureDevice) {
        captureDevice.subjectAreaChangeMonitoringEnabled=YES;
    }];
    NSNotificationCenter *notificationCenter= [NSNotificationCenter defaultCenter];
    //捕獲區域發生改變
    [notificationCenter addObserver:self selector:@selector(areaChange:) name:AVCaptureDeviceSubjectAreaDidChangeNotification object:captureDevice];
}

-(void)removeNotificationFromCaptureDevice:(AVCaptureDevice *)captureDevice{
    NSNotificationCenter *notificationCenter= [NSNotificationCenter defaultCenter];
    [notificationCenter removeObserver:self name:AVCaptureDeviceSubjectAreaDidChangeNotification object:captureDevice];
}

-(void)removeNotification{
    NSNotificationCenter *notificationCenter= [NSNotificationCenter defaultCenter];
    [notificationCenter removeObserver:self];
}

-(void)addNotificationToCaptureSession:(AVCaptureSession *)captureSession{
    NSNotificationCenter *notificationCenter= [NSNotificationCenter defaultCenter];
    //會話出錯
    [notificationCenter addObserver:self selector:@selector(sessionRuntimeError:) name:AVCaptureSessionRuntimeErrorNotification object:captureSession];
}

//屏幕旋轉時調整視頻預覽圖層的方向
-(void)willRotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration{
    AVCaptureConnection *captureConnection=[self.captureVideoPreviewLayer connection];
    captureConnection.videoOrientation=(AVCaptureVideoOrientation)toInterfaceOrientation;
}
//旋轉后重新設置大小
-(void)didRotateFromInterfaceOrientation:(UIInterfaceOrientation)fromInterfaceOrientation{
    _captureVideoPreviewLayer.frame=self.contentView.bounds;
}

//獲取指定位置的攝像頭
- (AVCaptureDevice *)getCameraDeviceWithPosition:(AVCaptureDevicePosition) positon{

    NSArray * cameras = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
    for (AVCaptureDevice * camera in cameras) {
        if ([camera position] == positon) {
            return camera;
        }
    }
    return nil;
}

//屬性改變操作
- (void)changeDeviceProperty:(PropertyChangeBlock ) propertyChange{
   
    AVCaptureDevice * captureDevice = [self.captureDeviceInput device];
    NSError * error;
    //注意改變設備屬性前一定要首先調用lockForConfiguration:調用完之后使用unlockForConfiguration方法解鎖
    if ([captureDevice lockForConfiguration:&error]) {
      
        propertyChange(captureDevice);
        [captureDevice unlockForConfiguration];
        
    } else {
        
        NSLog(@"設置設備屬性過程發生錯誤，錯誤信息：%@", error.localizedDescription);
    }
}

//設置閃光燈模式
- (void)setFlashMode:(AVCaptureFlashMode ) flashMode{
    [self changeDeviceProperty:^(AVCaptureDevice *captureDevice) {
        if ([captureDevice isFlashModeSupported:flashMode]) {
            [captureDevice setFlashMode:flashMode];
        }
    }];
}

//聚焦模式
- (void)setFocusMode:(AVCaptureFocusMode) focusMode{
    [self changeDeviceProperty:^(AVCaptureDevice *captureDevice) {
        if ([captureDevice isFocusModeSupported:focusMode]) {
            [captureDevice setFocusMode:focusMode];
        }
    }];
}

//設置曝光模式
- (void)setExposureMode:(AVCaptureExposureMode) exposureMode{
    [self changeDeviceProperty:^(AVCaptureDevice *captureDevice) {
        if ([captureDevice isExposureModeSupported:exposureMode]) {
            [captureDevice setExposureMode:exposureMode];
        }
    }];
}

//設置聚焦點
- (void)focusWithMode:(AVCaptureFocusMode)focusMode exposureMode:(AVCaptureExposureMode)exposureMode atPoint:(CGPoint)point{
    [self changeDeviceProperty:^(AVCaptureDevice *captureDevice) {
        if ([captureDevice isFocusModeSupported:focusMode]) {
            [captureDevice setFocusMode:AVCaptureFocusModeAutoFocus];
        }
        
        if ([captureDevice isFocusPointOfInterestSupported]) {
            [captureDevice setFocusPointOfInterest:point];
        }
        
        if ([captureDevice isExposureModeSupported:exposureMode]) {
            [captureDevice setExposureMode:AVCaptureExposureModeAutoExpose];
        }
        
        if ([captureDevice isExposurePointOfInterestSupported]) {
            [captureDevice setExposurePointOfInterest:point];
        }
        
    }];
}

//添加點擊手勢，點按時聚焦
- (void)addGenstureRecognizer{
    UITapGestureRecognizer * tapGesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(tapScreen:)];
    [self.contentView addGestureRecognizer:tapGesture];
}

//設置閃關燈按鈕狀態
- (void)setFlashModeButtonStatus{
    
    AVCaptureDevice * captureDevice = [self.captureDeviceInput device];
    AVCaptureFlashMode flashMode = captureDevice.flashMode;
    if ([captureDevice isFlashAvailable]) {
        self.flashAutoButton.hidden = NO;
        self.flashOnButton.hidden  = NO;
        self.flashOffButton.hidden = NO;
        self.flashAutoButton.enabled = YES;
        self.flashOnButton.enabled = YES;
        self.flashOffButton.enabled = YES;
        
        switch (flashMode) {
            case AVCaptureFlashModeAuto:
                self.flashAutoButton.enabled = NO;
                break;
            case AVCaptureFlashModeOn:
                self.flashOnButton.enabled = NO;
                break;
            case AVCaptureFlashModeOff:
                self.flashOffButton.enabled = NO;
                break;
            default:
                break;
        }
    } else {
        self.flashAutoButton.hidden = YES;
        self.flashOnButton.hidden   = YES;
        self.flashOffButton.hidden  = YES;
    }
    
}

//設置聚焦光標位置
- (void)setFocusCursorWithPoint:(CGPoint)point{
    
    self.focusCursor.center = point;
    self.focusCursor.transform = CGAffineTransformMakeScale(1.5, 1.5);
    self.focusCursor.alpha = 1.0;
    [UIView animateWithDuration:1.0 animations:^{
        self.focusCursor.transform = CGAffineTransformIdentity;
    } completion:^(BOOL finished) {
        self.focusCursor.alpha=0;
    }];
}

/**
 *  設備連接成功
 *
 *  @param notification 通知對象
 */
-(void)deviceConnected:(NSNotification *)notification{
    NSLog(@"設備已連接...");
}
/**
 *  設備連接斷開
 *
 *  @param notification 通知對象
 */
-(void)deviceDisconnected:(NSNotification *)notification{
    NSLog(@"設備已斷開.");
}
/**
 *  捕獲區域改變
 *
 *  @param notification 通知對象
 */
-(void)areaChange:(NSNotification *)notification{
    NSLog(@"捕獲區域改變...");
}

/**
 *  會話出錯
 *
 *  @param notification 通知對象
 */
-(void)sessionRuntimeError:(NSNotification *)notification{
    NSLog(@"會話發生錯誤.");
}

#pragma mark - 點擊方法
- (void)tapScreen:(UITapGestureRecognizer *) tapGesture{

    CGPoint point = [tapGesture locationInView:self.contentView];
    //將UI坐標轉化為攝像頭坐標
    CGPoint cameraPoint = [self.captureVideoPreviewLayer captureDevicePointOfInterestForPoint:point];
    point.y +=124;
    [self setFocusCursorWithPoint:point];
    [self focusWithMode:AVCaptureFocusModeAutoFocus exposureMode:AVCaptureExposureModeAutoExpose atPoint:cameraPoint];
}

- (void)clickTakeButton:(UIButton *)sender{

    //根據設備輸出獲得連接
    AVCaptureConnection *captureConnection=[self.captureStillImageOutput connectionWithMediaType:AVMediaTypeVideo];
    //根據連接取得設備輸出的數據
    [self.captureStillImageOutput captureStillImageAsynchronouslyFromConnection:captureConnection completionHandler:^(CMSampleBufferRef imageDataSampleBuffer, NSError *error) {
        if (imageDataSampleBuffer) {
            NSData *imageData=[AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageDataSampleBuffer];
            UIImage *image=[UIImage imageWithData:imageData];
            UIImageWriteToSavedPhotosAlbum(image, nil, nil, nil);

        }
        
    }];
}

// 打開閃關燈
- (void)clickFlashOnButton:(UIButton *)sender{
    [self setFlashMode:AVCaptureFlashModeOn];
    [self setFlashModeButtonStatus];

}

//關閉閃光燈
- (void)clickFlashOffButton:(UIButton *)sender{
    [self setFlashMode:AVCaptureFlashModeOff];
    [self setFlashModeButtonStatus];

}

//自動閃關燈開起
- (void)clickFlashAutoButton:(UIButton *)sender{
    [self setFlashMode:AVCaptureFlashModeAuto];
    [self setFlashModeButtonStatus];
}

//切換攝像頭
- (void)clikcExchangeCamera:(UIButton *)sender{
    AVCaptureDevice * currentDevice = [self.captureDeviceInput device];
    AVCaptureDevicePosition currentPosition = [currentDevice position];
    [self removeNotificationFromCaptureDevice:currentDevice];
    AVCaptureDevice * toChangeDevice;
    AVCaptureDevicePosition  toChangePosition = AVCaptureDevicePositionFront;
    if (currentPosition==AVCaptureDevicePositionUnspecified||currentPosition==AVCaptureDevicePositionFront) {
        toChangePosition = AVCaptureDevicePositionBack;
    }
    toChangeDevice = [self getCameraDeviceWithPosition:toChangePosition];
    [self addNotificationToCaptureDevice:toChangeDevice];
    
    //獲得要調整到設備輸入對象
    AVCaptureDeviceInput * toChangeDeviceInput = [[AVCaptureDeviceInput alloc]initWithDevice:toChangeDevice error:nil];
    
    //改變會話到配置前一定要先開啟配置，配置完成后提交配置改變
    [self.captureSession beginConfiguration];
    //移除原有輸入對象
    [self.captureSession removeInput:self.captureDeviceInput];
    //添加新的輸入對象
    if ([self.captureSession canAddInput:toChangeDeviceInput]) {
        [self.captureSession addInput:toChangeDeviceInput];
        self.captureDeviceInput=toChangeDeviceInput;
    }
    
    //提交新的輸入對象
    [self.captureSession commitConfiguration];
    [self setFlashModeButtonStatus];
}

- (void)clickVideoButton:(UIButton *)sender{

    //根據設備輸出獲得連接
    AVCaptureConnection *captureConnection=[self.captureMovieFileOutPut connectionWithMediaType:AVMediaTypeVideo];
    //根據連接取得設備輸出的數據
    if (![self.captureMovieFileOutPut isRecording]) {
  //      self.enableRotation=NO;
        //如果支持多任務則則開始多任務
        if ([[UIDevice currentDevice] isMultitaskingSupported]) {
            self.backgroundTaskIdentifier=[[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:nil];
        }
        //預覽圖層和視頻方向保持一致
        captureConnection.videoOrientation=[self.captureVideoPreviewLayer connection].videoOrientation;
        NSString *outputFielPath=[NSTemporaryDirectory() stringByAppendingString:@"myMovie.mov"];
        NSLog(@"save path is :%@",outputFielPath);
        NSURL *fileUrl=[NSURL fileURLWithPath:outputFielPath];
        [self.captureMovieFileOutPut startRecordingToOutputFileURL:fileUrl recordingDelegate:self];
    }
    else{
        [self.captureMovieFileOutPut stopRecording];//停止錄制
    }
}

#pragma mark - UI相關和布局
- (void)setupUI{
    
    [self.view addSubview:self.contentView];
    self.contentView.frame = CGRectMake(0, 124, ScreenWith, ScreenHeight-60-124);
    
    self.takeButton = [self createCustomButtonWithName:@"拍照"];
    [self.takeButton addTarget:self action:@selector(clickTakeButton:) forControlEvents:UIControlEventTouchUpInside];
    self.takeButton.frame = CGRectMake(ScreenWith/2-30, ScreenHeight-60, 60, 60);
    [self.view addSubview:self.takeButton];
    
    self.videoButton = [self createCustomButtonWithName:@"錄像"];
    [self.videoButton addTarget:self action:@selector(clickVideoButton:) forControlEvents:UIControlEventTouchUpInside];
    self.videoButton.frame = CGRectMake(ScreenWith-80, ScreenHeight-60, 60, 60);
    [self.view addSubview:self.videoButton];

    
    CGFloat margin = ((ScreenWith - 4*60)/5);
    self.flashOnButton = [self createCustomButtonWithName:@"打開閃光燈"];
    [self.flashOnButton addTarget:self action:@selector(clickFlashOnButton:) forControlEvents:UIControlEventTouchUpInside];
    self.flashOnButton.frame = CGRectMake(margin, 64, 60, 60);
    [self.view addSubview:self.flashOnButton];
    
    self.flashOffButton = [self createCustomButtonWithName:@"關閉閃光燈"];
    [self.flashOffButton addTarget:self action:@selector(clickFlashOffButton:) forControlEvents:UIControlEventTouchUpInside];
    self.flashOffButton.frame = CGRectMake(60+2*margin, 64, 60, 60);
    [self.view addSubview:self.flashOffButton];
    
    self.flashAutoButton = [self createCustomButtonWithName:@"自動閃光燈"];
    [self.flashAutoButton addTarget:self action:@selector(clickFlashAutoButton:) forControlEvents:UIControlEventTouchUpInside];
    self.flashAutoButton.frame = CGRectMake(2*60+3*margin, 64, 60, 60);
    [self.view addSubview:self.flashAutoButton];
    
    self.exchangeCamera = [self createCustomButtonWithName:@"切換"];
    [self.exchangeCamera addTarget:self action:@selector(clikcExchangeCamera:) forControlEvents:UIControlEventTouchUpInside];
    self.exchangeCamera.frame = CGRectMake(ScreenWith-60-margin, 64, 60, 60);
    [self.view addSubview:self.exchangeCamera];
    
    self.focusCursor = [[UIImageView alloc]initWithFrame:CGRectMake(0, 0, 60, 60)];
    self.focusCursor.backgroundColor = [UIColor redColor];
    self.focusCursor.layer.cornerRadius = 30;
    self.focusCursor.layer.masksToBounds = YES;
    [self.view addSubview:self.focusCursor];
    
    
}

- (UIView *)contentView{
    if (!_contentView) {
        _contentView = [[UIView alloc] init];
    }
    return _contentView;
}

- (UIButton *)createCustomButtonWithName:(NSString *)name{
    UIButton * button = [UIButton buttonWithType:UIButtonTypeCustom];
    [button setTitle:name forState:UIControlStateNormal];
    button.backgroundColor = [UIColor redColor];
    button.layer.cornerRadius = 30;
    button.layer.masksToBounds = YES;
    return button;
}

效果圖