【iOS】0行代码实现评分星星视图

最终效果

要求：

• Platform: iOS7.0+
• Language: Objective-C
• Editor: Xcode6.0+

实现

• 思路
  UIPogressView + UIImage

总得来说，就利用progressView的两个属性：_progressImage【顶图】和_trackImage【底图】实现不同进度值下的评分效果。

• 属性设置

  
  
  属性设置

• 交互逻辑代码

注意：_stepValue是指滑动过程中的最小步进值，0.5表示半颗星，1表示一颗星，要求0 < _stepValue <= 1。

-(void)setProgressImage:(UIImage *)progressImage{
    super.progressImage = [self configureImage:progressImage];
}

-(void)setTrackImage:(UIImage *)trackImage{
    super.trackImage = [self configureImage: trackImage];
}

// 重新计算设置图，使其符合平铺要求
- (UIImage*)configureImage:(UIImage*)image
{
    CGFloat width = self.bounds.size.width / 5;
    CGSize size = CGSizeMake(width, width);
    
    UIGraphicsBeginImageContextWithOptions(size, false, image.scale);
    [image drawInRect:CGRectMake(0, 0, size.width, size.height)];
    UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    
    return [newImage resizableImageWithCapInsets:UIEdgeInsetsZero resizingMode:UIImageResizingModeTile];
}

// 设置progressView的进度
-(void)updateProgressWithTouches: (NSSet<UITouch *> *)touches isMoved: (BOOL)isMoved{
    UITouch *touch = touches.anyObject;
    CGPoint loc = [touch locationInView:_progressView];
    
    float value = loc.x / _progressView.bounds.size.width;
    if (value < 0) {
        return;
    }
    float progress = (_stepValue == 0) ? value : ceil(value * 5 / _stepValue) * _stepValue / 5;
    progress = MIN(progress, 1);

    _progressView.progress = progress;
}

-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{
    [self updateProgressWithTouches:touches isMoved:false];
}

-(void)touchesEnded:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{
    [self updateProgressWithTouches:touches isMoved:false];
}

-(void)touchesMoved:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{
    [self updateProgressWithTouches:touches isMoved:true];
}

-(void)touchesCancelled:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{
    [self updateProgressWithTouches:touches isMoved:false];
}

• 注意

在设置NSLayout时，设置progressView的高度要和icon_star保持一致，宽度为图片的倍数值，否则会显示错乱。

github

https://github.com/BackWorld/HYStarView

本文只是给读者展示了一种独特的最简单的实现方式，如果对你有帮助，别忘了点个❤️哦。