iOS项目017.转盘抽奖

效果图

项目结构

匿名类目 vs IBOutlet

只有在.m文件中建立了匿名类目，才能连接storyBoard中的IBOutlet

view.m

@interface WheelView ()
@property (weak, nonatomic) IBOutlet UIImageView *centerView;
@end

加载xib文件

+ (instancetype)wheelView{
return [[[NSBundle mainBundle] loadNibNamed:@"WheelView" owner:nil options:nil] lastObject];
}

裁剪图片

UIImage *img = [UIImage imageNamed:@"LuckyAstrology"];
CGFloat smallW = img.size.width / 12 * [UIScreen mainScreen].scale;
CGFloat smallH = img.size.height * [UIScreen mainScreen].scale; 
CGRect smallRect = CGRectMake(index * smallW, 0, smallW, smallH);
CGImageRef smallImage = CGImageCreateWithImageInRect(img.CGImage, smallRect);
[btn setImage:[UIImage imageWithCGImage:smallImage] forState:UIControlStateNormal];