ios给view设置背景颜色的正确方式

  UIView *back=[[UIViewalloc]initWithFrame:CGRectMake(0,0, WIDTH,HEIGHT)];

    UIImage *image=[UIImageimageNamed:@"background.jpg"];

    back.layer.contents=(__bridgeid _Nullable)(image.CGImage);

    back.layer.backgroundColor=[UIColorclearColor].CGColor;

住：直接调用background方法，图片不会被拉伸，所以会导致图片显示异常