在使用AVCaptureSession自定义相机的时候，发现无论横竖拍出来，照片的方向总是不对，参考了下面的两个链接的方法依旧行不通，然后自己想了个办法去解决。
is-uiimage-imagewithciimagescaleorientation-broken-on-ios10
how-to-rotate-a-uiimage-90-degrees
通过使用重力加速计判断手机旋转的方向，再去设置AVCaptureConnection的videoOrientation属性，代码如下：
@interface FIDCameraHelper ()
@property (nonatomic,strong) CMMotionManager *motionManager;
@property (nonatomic,assign) UIImageOrientation orientation;
@end
@implementation FIDCameraHelper
- (CMMotionManager *)motionManager
{
if (!_motionManager)
{
_motionManager = [[CMMotionManager alloc]init];
}
return _motionManager;
}
//启动重力加速计
+ (void)startUpdateAccelerometerResult:(void (^)(UIImageOrientation orientation))result
{
if ([sharedManager.motionManager isAccelerometerAvailable]
[sharedManager.motionManager setAccelerometerUpdateInterval:0.1];
[sharedManager.motionManager startAccelerometerUpdatesToQueue:[NSOperationQueue currentQueue] withHandler:^(CMAccelerometerData *accelerometerData, NSError *error)
{
double x = accelerometerData.acceleration.x;
double y = accelerometerData.acceleration.y;
if (fabs(y) >= fabs(x))
{
if (y >= 0){
//Down
if (result) {
result(UIImageOrientationDown);
}
}
else{
//Portrait
if (result) {
result(UIImageOrientationUp);
}
}
}
else
{
if (x >= 0){
//Right
if (result) {
result(UIImageOrientationRight);
}
}
else{
//Left
if (result) {
result(UIImageOrientationLeft);
}
}
}
}];
}
}
- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection
{
CVPixelBufferRef pixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
CFDictionaryRef attachments = CMCopyDictionaryOfAttachments(kCFAllocatorDefault, sampleBuffer, kCMAttachmentMode_ShouldNotPropagate);
CIImage *ciImage = [[CIImage alloc] initWithCVPixelBuffer:pixelBuffer options:(NSDictionary *)CFBridgingRelease(attachments)];
//根据方向设置videoOrientation
switch (self.orientation) {
case UIImageOrientationUp:
{
connection.videoOrientation = AVCaptureVideoOrientationPortrait;
break;
}
case UIImageOrientationDown:
{
connection.videoOrientation = AVCaptureVideoOrientationPortraitUpsideDown;
break;
}
case UIImageOrientationLeft:
{
connection.videoOrientation = AVCaptureVideoOrientationLandscapeRight;
break;
}
case UIImageOrientationRight:
{
connection.videoOrientation = AVCaptureVideoOrientationLandscapeLeft;
break;
}
default:
break;
}
self.cameraImage = [UIImage imageWithCIImage:ciImage scale:1.0 orientation:self.orientation];
}
@end
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