如果我从服务器下载一些图像,是否应该调整其大小以支持视网膜设计?

如果现在不能使用-@ 2x,如何设置要显示的正确图像?

更新:

如果缓存图像,则需要在下载后和缓存之前调整图像的大小,并缓存2张常规图像和@ 2x?

最佳答案

您的应用应以视网膜大小检索这些图像。要获得非视网膜尺寸,您可以手动缩放然后保存。这里是示例代码:

UIImage *image = [UIImage imageNamed:@"yourRetinaImage@2x.png"];

// set non-retina size from current image
CGSize size = CGSizeMake(image.size.width / 2., image.size.height / 2.);


/** scale the image */

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), image.CGImage);

UIImage *scaledImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();


/** save scaled image */

NSString *basePath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
// save with same name but without suffix "@2x"
NSString *filePath = [NSString stringWithFormat:@"%@/%@", basePath, @"yourRetinaImage"];

@try {
    [UIImagePNGRepresentation(scaledImage) writeToFile:filePath options:NSAtomicWrite error:nil];
} @catch (NSException *exception) {
    NSLog(@"error while saving non-retina image with exception %@", exception);
}

10-06 05:05
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