转盘

代码

主要的实现要点：

1> 自定义按钮的imageRectForContentRect

- (CGRect)imageRectForContentRect:(CGRect)contentRect{
    CGFloat imageWidth = 40;
    CGFloat imageHeight = 47;
    CGFloat x = (contentRect.size.width- imageWidth)*0.5;
//    CGFloat y = (contentRect.size.height-imageHeight)*0.5;
    CGFloat y =20;
    return CGRectMake(x, y, imageWidth, imageHeight);
}
/**
 determines whether the receiver is highlighted.
 */
- (void)setHighlighted:(BOOL)highlighted{//不做任何事情的时候，可以去掉按钮的高亮状态的一些效果

}

2>添加转盘按钮

    //1. 设置选中按钮时的背景图片-－选中状态需要自己管理

        [btn setBackgroundImage:[UIImage imageNamed:@"LuckyRototeSelected"] forState:UIControlStateSelected];

        //2.设置正常状态的背景图片

        [btn setImage:[self clipImageWithName:imageForNormalName index:i count:KButtonCount] forState:UIControlStateNormal];

        //设置选中的背景图片

3> 图片的裁剪（从大图中裁剪有规律的小图）

#pragma  mark - 按钮的图片裁剪

/**
 裁剪的图片名称 name
 裁剪第几个小图片 index
 大图片的小图片个数 count

 */

- (UIImage*) clipImageWithName:(NSString*)name index:(int)i count:(float)count{
    //裁剪的大图片
    UIImage *bigImage = [UIImage imageNamed:name];
    //设置裁剪的尺寸
    CGFloat scale =[UIScreen mainScreen].scale;
    //将点转换为像素点
    /*
     For standard-resolution displays, the scale factor is 1.0 and one point equals one pixel. For Retina displays, the scale factor is 2.0 and one point is represented by four pixels.
     */
    CGFloat smallImageWidth = bigImage.size.width/count*scale;
    CGFloat smallImageHeight = bigImage.size.height*scale;
    CGFloat smallImageX = i*smallImageWidth;

    CGRect clipRect =  CGRectMake(smallImageX, 0, smallImageWidth, smallImageHeight);
    CGImageRef smallImageRef = CGImageCreateWithImageInRect(bigImage.CGImage, clipRect);
    return [UIImage imageWithCGImage:smallImageRef];
}

4>快速旋转： 孤度的计算

#pragma  mark - 快速旋转
- (IBAction)chooseNO:(UIButton *)sender {
    //3、快点旋转
    /** 核心动画的缺点是改变不了真是的属性*/
    CABasicAnimation *animation = [CABasicAnimation animation];
    //设置动画对象属性
    [animation setKeyPath:@"transform.rotation"];
    [animation setToValue:@(M_PI*3)];
    [animation setDuration:0.5];
    [animation setDelegate:self];
    [self.roattionImageView.layer addAnimation:animation forKey:nil];

}