iOS开发-解决拍照后照片旋转90度的有关问题（附Swift版本）
iOS开发--解决拍照后照片旋转90度的问题（附Swift版本）
当我们使用相机拍照后，调用UIImagePickerController的delegate方法，如下代码所示：
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info { UIImage *image = [info objectForKey:UIImagePickerControllerOriginalImage]; }
通过UIImagePickerControllerOriginalImage这个key从info字典中可以获取到拍照后的UIImage，但如果断点查看图片，我们会发现图片是旋转了90度的。
不过如果直接使用图片，比如使用这个UIImage赋值给一个UIImageView的实例，显示出来的图片是完全没有问题的。
但如果使用这个UIImage作他用，比如上传到服务器，就会出现问题了，上传到服务器的图片也是旋转了90度的。
原因：通过UIImagePickerControllerOriginalImage这个key从info字典中可以获取到拍照后的UIImage，其imageOrientation属性默认是UIImageOrientationRight，也就是说默认就是向左侧旋转了90度的。
解决方法如下:
方法一：创建UIImagePickerController实例的时候，设置实例的一个属性allowsEditing为YES，设了这个值，拍完照片后会在照片上出现一个框框，可以对照片的裁剪编辑。在UIImagePickerController的代理方法中取照片的时候也就别用UIImagePickerControllerOriginalImage这个key来取了，而要用UIImagePickerControllerEditedImage，此时取出来的照片，它的imageOrientation是UIImageOrientationUp而不是默认的UIImageOrientationRight了。
方法二：有一个专门针对UIImage旋转这个问题的很好的Category，代码如下：
OC版本：
UIImage+fixOrientation.h
#import <UIKit/UIKit.h> @interface UIImage (fixOrientation) - (UIImage *)fixOrientation; @end
UIImage+fixOrientation.m
#import "UIImage+fixOrientation.h" @implementation UIImage (fixOrientation) - (UIImage *)fixOrientation { // No-op if the orientation is already correct if (self.imageOrientation == UIImageOrientationUp) return self; // We need to calculate the proper transformation to make the image upright. // We do it in 2 steps: Rotate if Left/Right/Down, and then flip if Mirrored. CGAffineTransform transform = CGAffineTransformIdentity; switch (self.imageOrientation) { case UIImageOrientationDown: case UIImageOrientationDownMirrored: transform = CGAffineTransformTranslate(transform, self.size.width, self.size.height); transform = CGAffineTransformRotate(transform, M_PI); break; case UIImageOrientationLeft: case UIImageOrientationLeftMirrored: transform = CGAffineTransformTranslate(transform, self.size.width, 0); transform = CGAffineTransformRotate(transform, M_PI_2); break; case UIImageOrientationRight: case UIImageOrientationRightMirrored: transform = CGAffineTransformTranslate(transform, 0, self.size.height); transform = CGAffineTransformRotate(transform, -M_PI_2); break; } switch (self.imageOrientation) { case UIImageOrientationUpMirrored: case UIImageOrientationDownMirrored: transform = CGAffineTransformTranslate(transform, self.size.width, 0); transform = CGAffineTransformScale(transform, -1, 1); break; case UIImageOrientationLeftMirrored: case UIImageOrientationRightMirrored: transform = CGAffineTransformTranslate(transform, self.size.height, 0); transform = CGAffineTransformScale(transform, -1, 1); break; } // Now we draw the underlying CGImage into a new context, applying the transform // calculated above. CGContextRef ctx = CGBitmapContextCreate(NULL, self.size.width, self.size.height, CGImageGetBitsPerComponent(self.CGImage), 0, CGImageGetColorSpace(self.CGImage), CGImageGetBitmapInfo(self.CGImage)); CGContextConcatCTM(ctx, transform); switch (self.imageOrientation) { case UIImageOrientationLeft: case UIImageOrientationLeftMirrored: case UIImageOrientationRight: case UIImageOrientationRightMirrored: // Grr... CGContextDrawImage(ctx, CGRectMake(0,0,self.size.height,self.size.width), self.CGImage); break; default: CGContextDrawImage(ctx, CGRectMake(0,0,self.size.width,self.size.height), self.CGImage); break; } // And now we just create a new UIImage from the drawing context CGImageRef cgimg = CGBitmapContextCreateImage(ctx); UIImage *img = [UIImage imageWithCGImage:cgimg]; CGContextRelease(ctx); CGImageRelease(cgimg); return img; } @end
Swift版本：
import UIKit
extension UIImage {
// 修复图片旋转
func fixOrientation() -> UIImage {
if self.imageOrientation == .up {
return self
}
var transform = CGAffineTransform.identity
switch self.imageOrientation {
case .down, .downMirrored:
transform = transform.translatedBy(x: self.size.width, y: self.size.height)
transform = transform.rotated(by: .pi)
break
case .left, .leftMirrored:
transform = transform.translatedBy(x: self.size.width, y: 0)
transform = transform.rotated(by: .pi / 2)
break
case .right, .rightMirrored:
transform = transform.translatedBy(x: 0, y: self.size.height)
transform = transform.rotated(by: -.pi / 2)
break
default:
break
}
switch self.imageOrientation {
case .upMirrored, .downMirrored:
transform = transform.translatedBy(x: self.size.width, y: 0)
transform = transform.scaledBy(x: -1, y: 1)
break
case .leftMirrored, .rightMirrored:
transform = transform.translatedBy(x: self.size.height, y: 0);
transform = transform.scaledBy(x: -1, y: 1)
break
default:
break
}
let ctx = CGContext(data: nil, width: Int(self.size.width), height: Int(self.size.height), bitsPerComponent: self.cgImage!.bitsPerComponent, bytesPerRow: 0, space: self.cgImage!.colorSpace!, bitmapInfo: self.cgImage!.bitmapInfo.rawValue)
ctx?.concatenate(transform)
switch self.imageOrientation {
case .left, .leftMirrored, .right, .rightMirrored:
ctx?.draw(self.cgImage!, in: CGRect(x: CGFloat(0), y: CGFloat(0), width: CGFloat(size.height), height: CGFloat(size.width)))
break
default:
ctx?.draw(self.cgImage!, in: CGRect(x: CGFloat(0), y: CGFloat(0), width: CGFloat(size.width), height: CGFloat(size.height)))
break
}
let cgimg: CGImage = (ctx?.makeImage())!
let img = UIImage(cgImage: cgimg)
return img
}
}