我正在开发适用于iPad的iOS应用。 有没有什么办法来旋转一个UIImage 90度，然后将其添加到一个UIImageView？ 我已经尝试了很多不同的代码，但没有工作...
谢谢！
Answer 1:
您可以旋转UIImageView本身：
UIImageView *iv = [[UIImageView alloc] initWithImage:image];
iv.transform = CGAffineTransformMakeRotation(M_PI_2);
或者，如果你真的想改变形象，你可以使用代码这个答案 ，它的工作原理。
Answer 2:
要旋转像素，你可以使用下面的。 这产生具有旋转元数据的中间的UIImage和它呈现与换位宽度/高度尺寸的图像上下文。 将得到的图像具有旋转的像素（即底层CGImage）
- (UIImage*)rotateUIImage:(UIImage*)sourceImage clockwise:(BOOL)clockwise
{
CGSize size = sourceImage.size;
UIGraphicsBeginImageContext(CGSizeMake(size.height, size.width));
[[UIImage imageWithCGImage:[sourceImage CGImage] scale:1.0 orientation:clockwise ? UIImageOrientationRight : UIImageOrientationLeft] drawInRect:CGRectMake(0,0,size.height ,size.width)];
UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
有可以传递为取向参数，实现180度旋转和翻转等其他可能的值
Answer 3:
这将任何给定度旋转图像。
注意这个工程2x和3倍视网膜以及
- (UIImage *)imageRotatedByDegrees:(CGFloat)degrees {
CGFloat radians = DegreesToRadians(degrees);
UIView *rotatedViewBox = [[UIView alloc] initWithFrame:CGRectMake(0,0, self.size.width, self.size.height)];
CGAffineTransform t = CGAffineTransformMakeRotation(radians);
rotatedViewBox.transform = t;
CGSize rotatedSize = rotatedViewBox.frame.size;
UIGraphicsBeginImageContextWithOptions(rotatedSize, NO, [[UIScreen mainScreen] scale]);
CGContextRef bitmap = UIGraphicsGetCurrentContext();
CGContextTranslateCTM(bitmap, rotatedSize.width / 2, rotatedSize.height / 2);
CGContextRotateCTM(bitmap, radians);
CGContextScaleCTM(bitmap, 1.0, -1.0);
CGContextDrawImage(bitmap, CGRectMake(-self.size.width / 2, -self.size.height / 2 , self.size.width, self.size.height), self.CGImage );
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
Answer 4:
还有imageWithCIImage:scale:orientation ，如果你想旋转UIImage不是UIImageView
这些方向之一：
typedef enum {
UIImageOrientationUp,
UIImageOrientationDown, // 180 deg rotation
UIImageOrientationLeft, // 90 deg CW
UIImageOrientationRight, // 90 deg CCW
UIImageOrientationUpMirrored, // vertical flip
UIImageOrientationDownMirrored, // horizontal flip
UIImageOrientationLeftMirrored, // 90 deg CW then perform horizontal flip
UIImageOrientationRightMirrored, // 90 deg CCW then perform vertical flip
} UIImageOrientation;
Answer 5:
下面是@ RyanG的Objective C代码的一个扩展的UIImage迅速版本：
extension UIImage {
func rotate(byDegrees degree: Double) -> UIImage {
let radians = CGFloat(degree*M_PI)/180.0 as CGFloat
let rotatedViewBox = UIView(frame: CGRect(x: 0, y: 0, width: self.size.width, height: self.size.height))
let t = CGAffineTransform(rotationAngle: radians)
rotatedViewBox.transform = t
let rotatedSize = rotatedViewBox.frame.size
let scale = UIScreen.main.scale
UIGraphicsBeginImageContextWithOptions(rotatedSize, false, scale)
let bitmap = UIGraphicsGetCurrentContext()
CGContextTranslateCTM(bitmap, rotatedSize.width / 2, rotatedSize.height / 2);
bitmap!.rotate(by: radians);
bitmap!.scaleBy(x: 1.0, y: -1.0);
CGContextDrawImage(bitmap, CGRectMake(-self.size.width / 2, -self.size.height / 2 , self.size.width, self.size.height), self.CGImage );
let newImage = UIGraphicsGetImageFromCurrentImageContext()
return newImage
}
}
用法是image.rotate(degree) 。
Answer 6:
随着斯威夫特，您可以通过旋转图像：
var image: UIImage = UIImage(named: "headerBack.png")
var imageRotated: UIImage = UIImage(CGImage: image.CGImage, scale:1, orientation: UIImageOrientation.UpMirrored)
Answer 7:
UIImage *img = [UIImage imageWithName@"aaa.png"];
UIImage *image = [UIImage imageWithCGImage:img.CGImage scale:1.0 orientation:UIImageOrientationRight];
Answer 8:
这样做的另一个方法是再次渲染的UIImage使用核芯显卡。
一旦你的情况下，使用CGContextRotateCTM 。
更多信息这个苹果文档
Answer 9:
感谢杰森克罗克这个解决我的问题。 只有一个微小的修正，交换的高度和宽度在两个位置，不失真发生，即
UIGraphicsBeginImageContext(CGSizeMake(size.width, size.height));
[[UIImage imageWithCGImage:[sourceImage CGImage] scale:1.0 orientation:clockwise ? UIImageOrientationRight : UIImageOrientationLeft] drawInRect:CGRectMake(0,0,size.width,size.height)];
我的问题不能由CGContextRotateCTM来解决，我不知道为什么。 我的问题是我要传递我的形象到服务器，它是送花儿给人90度显示关闭。 如果你的图片会通过复制图像，你是在Mac上运行的MS Office程序在非苹果世界工作，你可以轻松地测试。
Answer 10:
这是当我想改变一个图像的方向我做了什么（顺时针旋转90度）。
//Checking for the orientation ie, image taken from camera is in portrait or not.
if(yourImage.imageOrientation==3)
{
//Image is in portrait mode.
yourImage=[self imageToRotate:yourImage RotatedByDegrees:90.0];
}
- (UIImage *)image:(UIImage *)imageToRotate RotatedByDegrees:(CGFloat)degrees
{
CGFloat radians = degrees * (M_PI / 180.0);
UIView *rotatedViewBox = [[UIView alloc] initWithFrame:CGRectMake(0,0, image.size.height, image.size.width)];
CGAffineTransform t = CGAffineTransformMakeRotation(radians);
rotatedViewBox.transform = t;
CGSize rotatedSize = rotatedViewBox.frame.size;
UIGraphicsBeginImageContextWithOptions(rotatedSize, NO, [[UIScreen mainScreen] scale]);
CGContextRef bitmap = UIGraphicsGetCurrentContext();
CGContextTranslateCTM(bitmap, rotatedSize.height / 2, rotatedSize.width / 2);
CGContextRotateCTM(bitmap, radians);
CGContextScaleCTM(bitmap, 1.0, -1.0);
CGContextDrawImage(bitmap, CGRectMake(-image.size.width / 2, -image.size.height / 2 , image.size.height, image.size.width), image.CGImage );
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
经旋转的图像可以是大小> = 15MB（从我的经验）的。 所以，你应该压缩它并使用它。 否则，你可能会遇到崩溃导致内存压力。 我用压缩代码如下。
NSData *imageData = UIImageJPEGRepresentation(yourImage, 1);
//1 - it represents the quality of the image.
NSLog(@"Size of Image(bytes):%d",[imageData length]);
//Here I used a loop because my requirement was, the image size should be <= 4MB.
//So put an iteration for more than 1 time upto when the image size is gets <= 4MB.
for(int loop=0;loop<100;loop++)
{
if([imageData length]>=4194304) //4194304 = 4MB in bytes.
{
imageData=UIImageJPEGRepresentation(yourImage, 0.3);
yourImage=[[UIImage alloc]initWithData:imageData];
}
else
{
NSLog(@"%d time(s) compressed.",loop);
break;
}
}
现在你yourImage可用于任何地方.. 快乐编码...
文章来源: How to rotate UIImage
