在我的iPhone应用程序中，我用相机拍了一张照片，然后我想把它调整为290*390像素。我用这个方法来调整图像的大小:
UIImage *newImage = [image _imageScaledToSize:CGSizeMake(290, 390)
interpolationQuality:1];
它工作得很好，但它是一个没有记录的功能，所以我不能再在iPhone OS4上使用它了。
所以…调整UIImage大小最简单的方法是什么?
当前回答
Rogerio Chaves的回答是一个快速扩展
func scaledTo(size: CGSize) -> UIImage{
UIGraphicsBeginImageContextWithOptions(size, false, 0.0);
self.draw(in: CGRect(x: 0, y: 0, width: size.width, height: size.height))
let newImage:UIImage = UIGraphicsGetImageFromCurrentImageContext()!
UIGraphicsEndImageContext()
return newImage
}
还有额外的好处
func scaledTo(height: CGFloat) -> UIImage{
let width = height*self.size.width/self.size.height
return scaledTo(size: CGSize(width: width, height: height))
}
其他回答
我也见过这样做(我在UIButtons的正常和选定状态下使用，因为按钮不会调整大小来适应)。功劳归于原作者。
首先创建一个空的。h和。m文件，分别命名为uiimageresize .h和uiimageresize .m
// Put this in UIImageResizing.h
@interface UIImage (Resize)
- (UIImage*)scaleToSize:(CGSize)size;
@end
// Put this in UIImageResizing.m
@implementation UIImage (Resize)
- (UIImage*)scaleToSize:(CGSize)size {
UIGraphicsBeginImageContext(size);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextTranslateCTM(context, 0.0, size.height);
CGContextScaleCTM(context, 1.0, -1.0);
CGContextDrawImage(context, CGRectMake(0.0f, 0.0f, size.width, size.height), self.CGImage);
UIImage* scaledImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return scaledImage;
}
@end
将.h文件包含在你将要使用该函数的.m文件中，然后像这样调用它:
UIImage* image = [UIImage imageNamed:@"largeImage.png"];
UIImage* smallImage = [image scaleToSize:CGSizeMake(100.0f,100.0f)];
(兼容Swift 4) iOS 10+和iOS < 10解决方案(如果可能，使用UIGraphicsGetImageFromCurrentImageContext)
/// Resizes an image
///
/// - Parameter newSize: New size
/// - Returns: Resized image
func scaled(to newSize: CGSize) -> UIImage {
let rect = CGRect(origin: .zero, size: newSize)
if #available(iOS 10, *) {
let renderer = UIGraphicsImageRenderer(size: newSize)
return renderer.image { _ in
self.draw(in: rect)
}
} else {
UIGraphicsBeginImageContextWithOptions(newSize, false, 0.0)
self.draw(in: rect)
let newImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return newImage!
}
}
如果你只想要一个更小的图像，不关心确切的大小:
+ (UIImage *)imageWithImage:(UIImage *)image scaledToScale:(CGFloat)scale
{
UIGraphicsBeginImageContextWithOptions(self.size, YES, scale);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetInterpolationQuality(context, kCGInterpolationHigh);
[self drawInRect:CGRectMake(0, 0, self.size.width, self.size.height)];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
将比例设置为0.25f将从800万相机中获得816 * 612的图像。
这里有一个UIImage+Scale的分类。
迅速回答:
func scaleDown(image: UIImage, withSize: CGSize) -> UIImage {
let scale = UIScreen.main.scale
UIGraphicsBeginImageContextWithOptions(withSize, false, scale)
image.draw(in: CGRect(x: 0, y: 0, width: withSize.width, height: withSize.height))
let newImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return newImage!
}
Rogerio Chaves的回答是一个快速扩展
func scaledTo(size: CGSize) -> UIImage{
UIGraphicsBeginImageContextWithOptions(size, false, 0.0);
self.draw(in: CGRect(x: 0, y: 0, width: size.width, height: size.height))
let newImage:UIImage = UIGraphicsGetImageFromCurrentImageContext()!
UIGraphicsEndImageContext()
return newImage
}
还有额外的好处
func scaledTo(height: CGFloat) -> UIImage{
let width = height*self.size.width/self.size.height
return scaledTo(size: CGSize(width: width, height: height))
}
