最近公司的项目中用到了相机，由于不用系统的相机，UI给的相机切图，必须自定义才可以。就花时间简单研究了一下相机的自定义。
相机属于系统硬件，这就需要我们来手动调用iPhone的相机硬件，分为以下步骤：
2016-03-30 上午9.51.09.png
1、首先声明以下对象
#import <AVFoundation/AVFoundation.h>
//捕获设备，通常是前置摄像头，后置摄像头，麦克风（音频输入）
@property (nonatomic, strong) AVCaptureDevice *device;
//AVCaptureDeviceInput 代表输入设备，他使用AVCaptureDevice 来初始化
@property (nonatomic, strong) AVCaptureDeviceInput *input;
//输出图片
@property (nonatomic ,strong) AVCaptureStillImageOutput *imageOutput;
//session：由他把输入输出结合在一起，并开始启动捕获设备（摄像头）
@property (nonatomic, strong) AVCaptureSession *session;
//图像预览层，实时显示捕获的图像
@property (nonatomic ,strong) AVCaptureVideoPreviewLayer *previewLayer;
2、初始化各个对象
- (void)cameraDistrict
{
// AVCaptureDevicePositionBack 后置摄像头
// AVCaptureDevicePositionFront 前置摄像头
self.device = [self cameraWithPosition:AVCaptureDevicePositionFront];
self.input = [[AVCaptureDeviceInput alloc] initWithDevice:self.device error:nil];
self.imageOutput = [[AVCaptureStillImageOutput alloc] init];
self.session = [[AVCaptureSession alloc] init];
// 拿到的图像的大小可以自行设定
// AVCaptureSessionPreset320x240
// AVCaptureSessionPreset352x288
// AVCaptureSessionPreset640x480
// AVCaptureSessionPreset960x540
// AVCaptureSessionPreset1280x720
// AVCaptureSessionPreset1920x1080
// AVCaptureSessionPreset3840x2160
self.session.sessionPreset = AVCaptureSessionPreset640x480;
//输入输出设备结合
if ([self.session canAddInput:self.input]) {
[self.session addInput:self.input];
}
if ([self.session canAddOutput:self.imageOutput]) {
[self.session addOutput:self.imageOutput];
}
//预览层的生成
self.previewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:self.session];
self.previewLayer.frame = CGRectMake(0, 64, SCREEN_WIDTH, SCREEN_HEIGHT-64);
self.previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
[self.view.layer addSublayer:self.previewLayer];
//设备取景开始
[self.session startRunning];
if ([_device lockForConfiguration:nil]) {
//自动闪光灯，
if ([_device isFlashModeSupported:AVCaptureFlashModeAuto]) {
[_device setFlashMode:AVCaptureFlashModeAuto];
}
//自动白平衡,但是好像一直都进不去
if ([_device isWhiteBalanceModeSupported:AVCaptureWhiteBalanceModeAutoWhiteBalance]) {
[_device setWhiteBalanceMode:AVCaptureWhiteBalanceModeAutoWhiteBalance];
}
[_device unlockForConfiguration];
}
}
根据前后置位置拿到相应的摄像头：
- (AVCaptureDevice *)cameraWithPosition:(AVCaptureDevicePosition)position{
NSArray *devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
for ( AVCaptureDevice *device in devices )
if ( device.position == position ){
return device;
}
return nil;
}
3、拍照拿到相应图片：
- (void)photoBtnDidClick
{
AVCaptureConnection *conntion = [self.imageOutput connectionWithMediaType:AVMediaTypeVideo];
if (!conntion) {
NSLog(@"拍照失败!");
return;
}
[self.imageOutput captureStillImageAsynchronouslyFromConnection:conntion completionHandler:^(CMSampleBufferRef imageDataSampleBuffer, NSError *error) {
if (imageDataSampleBuffer == nil) {
return ;
}
NSData *imageData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageDataSampleBuffer];
self.image = [UIImage imageWithData:imageData];
[self.session stopRunning];
[self.view addSubview:self.cameraImageView];
}
4、保存照片到相册：
#pragma - 保存至相册
- (void)saveImageToPhotoAlbum:(UIImage*)savedImage
{
UIImageWriteToSavedPhotosAlbum(savedImage, self, @selector(image:didFinishSavingWithError:contextInfo:), NULL);
}
// 指定回调方法
- (void)image: (UIImage *) image didFinishSavingWithError: (NSError *) error contextInfo: (void *) contextInfo
{
NSString *msg = nil ;
if(error != NULL){
msg = @"保存图片失败" ;
}else{
msg = @"保存图片成功" ;
}
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"保存图片结果提示"
message:msg
delegate:self
cancelButtonTitle:@"确定"
otherButtonTitles:nil];
[alert show];
}
5、前后置摄像头的切换
- (void)changeCamera{
NSUInteger cameraCount = [[AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo] count];
if (cameraCount > 1) {
NSError *error;
//给摄像头的切换添加翻转动画
CATransition *animation = [CATransition animation]；
animation.duration = .5f；
animation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
animation.type = @"oglFlip";
AVCaptureDevice *newCamera = nil;
AVCaptureDeviceInput *newInput = nil;
//拿到另外一个摄像头位置
AVCaptureDevicePosition position = [[_input device] position];
if (position == AVCaptureDevicePositionFront){
newCamera = [self cameraWithPosition:AVCaptureDevicePositionBack];
animation.subtype = kCATransitionFromLeft;//动画翻转方向
}
else {
newCamera = [self cameraWithPosition:AVCaptureDevicePositionFront];
animation.subtype = kCATransitionFromRight;//动画翻转方向
}
//生成新的输入
newInput = [AVCaptureDeviceInput deviceInputWithDevice:newCamera error:nil];
[self.previewLayer addAnimation:animation forKey:nil];
if (newInput != nil) {
[self.session beginConfiguration];
[self.session removeInput:self.input];
if ([self.session canAddInput:newInput]) {
[self.session addInput:newInput];
self.input = newInput;
} else {
[self.session addInput:self.input];
}
[self.session commitConfiguration];
} else if (error) {
NSLog(@"toggle carema failed, error = %@", error);
}
}
}
6、相机的其它参数设置
//AVCaptureFlashMode 闪光灯
//AVCaptureFocusMode 对焦
//AVCaptureExposureMode 曝光
//AVCaptureWhiteBalanceMode 白平衡
//闪光灯和白平衡可以在生成相机时候设置
//曝光要根据对焦点的光线状况而决定,所以和对焦一块写
//point为点击的位置
- (void)focusAtPoint:(CGPoint)point{
CGSize size = self.view.bounds.size;
CGPoint focusPoint = CGPointMake( point.y /size.height ,1-point.x/size.width );
NSError *error;
if ([self.device lockForConfiguration:&error]) {
//对焦模式和对焦点
if ([self.device isFocusModeSupported:AVCaptureFocusModeAutoFocus]) {
[self.device setFocusPointOfInterest:focusPoint];
[self.device setFocusMode:AVCaptureFocusModeAutoFocus];
}
//曝光模式和曝光点
if ([self.device isExposureModeSupported:AVCaptureExposureModeAutoExpose ]) {
[self.device setExposurePointOfInterest:focusPoint];
[self.device setExposureMode:AVCaptureExposureModeAutoExpose];
}
[self.device unlockForConfiguration];
//设置对焦动画
_focusView.center = point;
_focusView.hidden = NO;
[UIView animateWithDuration:0.3 animations:^{
_focusView.transform = CGAffineTransformMakeScale(1.25, 1.25);
}completion:^(BOOL finished) {
[UIView animateWithDuration:0.5 animations:^{
_focusView.transform = CGAffineTransformIdentity;
} completion:^(BOOL finished) {
_focusView.hidden = YES;
}];
}];
}
}
7、遇到的一些坑和解决办法
1) 前后置摄像头的切换
前后值不能切换，各种尝试找了半天没找到有原因。后来发现我在设置图片尺寸的时候设置为1080P [self.session canSetSessionPreset: AVCaptureSessionPreset1920x1080] ，前置摄像头并不支持这么大的尺寸，所以就不能切换前置摄像头。我验证了下 前置摄像头最高支持720P,720P以内可自由切换。 当然也可以在前后置摄像头切换的时候，根据前后摄像头来设置不同的尺寸，这里不在赘述。
2）焦点位置
CGPoint focusPoint = CGPointMake( point.y /size.height ,1-point.x/size.width );
setExposurePointOfInterest：focusPoint 函数后面Point取值范围是取景框左上角（0，0）到取景框右下角（1，1）之间。官方是这么写的：
The value of this property is a CGPoint that determines the receiver's focus point of interest, if it has one. A value of (0,0) indicates that the camera should focus on the top left corner of the image, while a value of (1,1) indicates that it should focus on the bottom right. The default value is (0.5,0.5).
我也试了按这个来但位置就是不对，只能按上面的写法才可以。前面是点击位置的y/PreviewLayer的高度，后面是1-点击位置的x/PreviewLayer的宽度
3）对焦和曝光
我在设置对焦是 先设置了模式setFocusMode，后设置对焦位置，就会导致很奇怪的现象，对焦位置是你上次点击的位置。所以一定要先设置位置，再设置对焦模式。
曝光同上
8、写在最后
附上demo常用到的基本就这么多，写的并不完善，有什么不对的，欢迎大家批评指正，共同学习。
网友评论
AVCaptureSessionPreset320x240 这个参数你可以设置上吗？
在我这是被注释掉了