ios UIButton设置高亮状态下的背景色

Posted 2020-10-26 孙富有(iOS工程师)

一，通过按钮的事件来设置背景色

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- (void)viewDidLoad {     [super viewDidLoad];           UIButton *button1 = [[UIButton alloc] initWithFrame:CGRectMake(50, 200, 100, 50)];     [button1 setTitle:@"button1" forState:UIControlStateNormal];     button1.backgroundColor = [UIColor orangeColor];     [button1 addTarget:self action:@selector(button1BackGroundHighlighted:) forControlEvents:UIControlEventTouchDown];     [button1 addTarget:self action:@selector(button1BackGroundNormal:) forControlEvents:UIControlEventTouchUpInside];     [self.view addSubview:button1]; }   //  button1普通状态下的背景色 - (void)button1BackGroundNormal:(UIButton *)sender {     sender.backgroundColor = [UIColor orangeColor]; }   //  button1高亮状态下的背景色 - (void)button1BackGroundHighlighted:(UIButton *)sender {     sender.backgroundColor = [UIColor greenColor]; }

二,通过把颜色转换为UIImage来作为按钮不同状态下的背景图片

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- (void)viewDidLoad {     [super viewDidLoad];           UIButton *button2 = [[UIButton alloc] initWithFrame:CGRectMake(170, 200, 100, 50)];     [button2 setTitle:@"button2" forState:UIControlStateNormal];     [button2 setBackgroundImage:[self imageWithColor:[UIColor redColor]] forState:UIControlStateNormal];     [button2 setBackgroundImage:[self imageWithColor:[UIColor grayColor]] forState:UIControlStateHighlighted];     [self.view addSubview:button2]; }   //  颜色转换为背景图片 - (UIImage *)imageWithColor:(UIColor *)color {     CGRect rect = CGRectMake(0.0f, 0.0f, 1.0f, 1.0f);     UIGraphicsBeginImageContext(rect.size);     CGContextRef context = UIGraphicsGetCurrentContext();           CGContextSetFillColorWithColor(context, [color CGColor]);     CGContextFillRect(context, rect);           UIImage *image = UIGraphicsGetImageFromCurrentImageContext();     UIGraphicsEndImageContext();           return image; }

 

三

1.首先，添加一个按钮在界面上，我们先设置好普通和高亮状态时的文字，还有圆角

    UIButton *button  = [[UIButton alloc] initWithFrame:CGRectMake(100, 100, 100, 40)];
    [button setTitle:@"normal" forState:UIControlStateNormal];
    [button setTitle:@"highlighted" forState:UIControlStateHighlighted];
    [button setBackgroundColor:[UIColor redColor]];
    button.layer.cornerRadius = 10.0f;
    button.layer.masksToBounds = YES;
    [self.view addSubview:button];

    // 添加观察者方法
    [self addObserver:button];

2.添加观察者

/**
 *  添加观察者
 *
 *  @param button 需要设置的按钮
 */
- (void)addObserver:(UIButton *)button {
    
    [button addObserver:self forKeyPath:@"highlighted" options:NSKeyValueObservingOptionNew context:nil];
}

3.接下来就是实现观察者方法

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary<NSString *,id> *)change context:(void *)context {
    
    UIButton *button = (UIButton *)object;
    if ([keyPath isEqualToString:@"highlighted"]) {
        if (button.highlighted) {
            [button setBackgroundColor:[UIColor blueColor]];
            return;
        }
        [button setBackgroundColor:[UIColor redColor]];
    }
}

这样我们就能在不使用图片的前提下，实现设置高亮和普通状态下的背景颜色
看下具体的效果