ios - "Inverse"来自 NSAttributedString 的 UIImage

Question

我从 NSAttributedString 创建了一个 UIImage:

UIFont *font = [UIFont systemFontOfSize:12.0f];
NSDictionary *attributes = @{NSFontAttributeName:font,
                             NSForegroundColorAttributeName:[UIColor greenColor]};

NSAttributedString *attributedString = [[NSAttributedString alloc] initWithString:title attributes:attributes];

// Create the image here
UIImage *image = [self imageFromAttributedString:attributedString];


#pragma mark - Get image from attributed string

- (UIImage *)imageFromAttributedString:(NSAttributedString *)text
{
    UIGraphicsBeginImageContextWithOptions(text.size, NO, 0.0);

    // draw in context
    [text drawAtPoint:CGPointMake(0.0, 0.0)];

    // transfer image
    UIImage *image = [UIGraphicsGetImageFromCurrentImageContext() imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];
    UIGraphicsEndImageContext();

    return image;
}

我的问题是，创建具有相同文本但“反转”的图像的最佳方式是什么，即 [UIColor greenColor] 和白色字体文本？

Answer 1

使用NSBackgroundColorAttributeName将背景设置为绿色，NSForegroundColorAttributeName将文本设置为白色。

文档包括:

NSString *const NSForegroundColorAttributeName;
NSString *const NSBackgroundColorAttributeName;

位于https://developer.apple.com/library/ios/documentation/UIKit/Reference/NSAttributedString_UIKit_Additions/Reference/Reference.html#//apple_ref/doc/uid/TP40011688