ios 中使用blend改变图片的颜色

在ios开发的过程中，我们经常会遇到这样的情况：当我们点击一个按钮时，按钮的背景颜色会发生变化，一般情况下我们会调用UIButton 的函数- (void)setBackgroundImage:(UIImage *)image forState:(UIControlState)state 来设置button在正常的情况下和按下时的背景颜色。此时我们就需要两张图片，制作图片的过程很复杂。

因此我们可以通过修改图片的背景颜色达到这样的效果：

blendMode在ios中是一个枚举类型：如下所示

enum CGBlendMode {

kCGBlendModeNormal,

kCGBlendModeMultiply,

kCGBlendModeScreen,

kCGBlendModeOverlay,

kCGBlendModeDarken,

kCGBlendModeLighten,

kCGBlendModeColorDodge,

kCGBlendModeColorBurn,

kCGBlendModeSoftLight,

kCGBlendModeHardLight,

kCGBlendModeDifference,

kCGBlendModeExclusion,

kCGBlendModeHue,

kCGBlendModeSaturation,

kCGBlendModeColor,

kCGBlendModeLuminosity,

kCGBlendModeClear,

kCGBlendModeCopy,

kCGBlendModeSourceIn,

kCGBlendModeSourceOut,

kCGBlendModeSourceAtop,

kCGBlendModeDestinationOver,

kCGBlendModeDestinationIn,

kCGBlendModeDestinationOut,

kCGBlendModeDestinationAtop,

kCGBlendModeXOR,

kCGBlendModePlusDarker,

kCGBlendModePlusLighter

};

注：premultiplied result, source, and destination colors with alpha; Ra,

Sa, and Da are the alpha components of these colors. R：表示结果 S表示包含alpha的原色， D表示含有alpha的目标色，Ra,Sa,Da分别是3个的alpja

（一）首先创建一个UIImage的类别：

@interface UIImage (Tint)

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

-(UIImage *) imageWithGradientTintClolor:(UIColor *)tintColor;

@end

（二）实现类别中的方法

// UIImage + Tint.m

// practice

// Created by user on 15/3/24.

#import "UIImage + Tint.h"

@implementation UIImage (Tint)

-(UIImage *)imageWithTintColor:(UIColor *)tintColor blendMode: (CGBlendMode) blendMode

{

UIGraphicsBeginImageContextWithOptions(self.size, NO,0.0f);

[tintColor setFill];

CGRect bounds = CGRectMake(0, 0, self.size.width, self.size.height);

UIRectFill(bounds);

[self drawInRect:bounds blendMode:blendMode alpha:1.0f];

if(blendMode != kCGBlendModeDestinationIn)

{

[self drawInRect:bounds blendMode:kCGBlendModeDestinationIn alpha:1.0f];

}

UIImage *image = UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();

return image;

}

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

{

return [self imageWithTintColor:tintColor blendMode:kCGBlendModeDestinationIn];／／保留原图的透明度

}

-(UIImage *) imageWithGradientTintClolor:(UIColor *)tintColor

{

return [self imageWithTintColor:tintColor blendMode:kCGBlendModeOverlay]; ／／保持背景色的明暗，就是灰暗信息

}

@end

（三）使用类别中的方法

UIImageView *imageView1 = [[UIImageView alloc]initWithFrame:CGRectMake(150, 150, 34, 34)];

UIImageView *imageView2 = [[UIImageView alloc]initWithFrame:CGRectMake(200, 200, 34, 34)];

UIImageView *imageView3 = [[UIImageView alloc]initWithFrame:CGRectMake(250,250, 34, 34)];

imageView1.image = [UIImage imageNamed:@"[email protected]"];

imageView2.image = [[UIImage imageNamed:@"auditing_btn[email protected]"] imageWithTintColor:[UIColor orangeColor]];

imageView3.image = [[UIImage imageNamed:@"auditing_btn_message_[email protected]"] imageWithGradientTintClolor:[UIColor orangeColor]];

[_firstView addSubview:imageView1];

[_firstView addSubview:imageView2];

[_firstView addSubview:imageView3];

程序运行之后的效果

ios 中使用blend改变图片的颜色

分别是3张图片的放在视图上显示的结果