UIImage 扩展功能

最新推荐文章于 2020-10-20 10:59:12 发布

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最新推荐文章于 2020-10-20 10:59:12 发布

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分类专栏：代码片段&类的讲解

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本文介绍了一种通过扩展UIImage类来改变图片颜色的方法。通过定义两个方法：imageWithTintColor: 和 imageWithGradientTintColor:，可以使用指定的颜色来为图片上色。这两个方法分别使用了不同的混合模式来达到预期的效果。

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1. 改变图片的颜色

定义image的扩展类

@interface UIImage (Tint)


- (UIImage *)imageWithTintColor:(UIColor *)tintColor;
- (UIImage *)imageWithGradientTintColor:(UIColor *)tintColor;


@end

类的实现

@implementation UIImage (Tint)


- (UIImage *)imageWithTintColor:(UIColor *)tintColor
{
    return [self imageWithTintColor:tintColor blendMode:kCGBlendModeDestinationIn];
}

- (UIImage *)imageWithGradientTintColor:(UIColor *)tintColor
{
    return [self imageWithTintColor:tintColor blendMode:kCGBlendModeMultiply];
}



//-----
- (UIImage *)imageWithTintColor:(UIColor *)tintColor blendMode:(CGBlendMode)blendMode
{
    
    // We want to keep alpha, set opaque to NO; Use 0.0f for scale to use the scale factor of the device’s main screen.
    UIGraphicsBeginImageContextWithOptions(self.size, NO, 0.0f);
    
    [tintColor setFill];
    CGRect bounds = CGRectMake(0, 0, self.size.width, self.size.height);
    UIRectFill(bounds);
    
    // Draw the tinted image in context
    
    [self drawInRect:bounds blendMode:blendMode alpha:1.0f];
    
    if (blendMode != kCGBlendModeDestinationIn) {
        [self drawInRect:bounds blendMode:kCGBlendModeDestinationIn alpha:1.0f];
    }
    
    UIImage *tintedImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    
    return tintedImage;
}

@end