实现倾斜文字水印背景

[[UIColor alloc] initWithPatternImage:xxxxx];

- (UIImage *)imageWithText:(NSString *)text{
    
    /**
     这里之所以外面再放一个UIView，是因为直接用label画图的话，旋转就不起作用了
     */
    UIView *view = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 100, 100)];
    view.backgroundColor = [UIColor clearColor];
    
    UILabel *label = [[UILabel alloc] initWithFrame:view.bounds];
    label.backgroundColor = [UIColor clearColor];
    label.textColor = [UIColor orangeColor];
    label.text = text;
    label.transform = CGAffineTransformMakeRotation(-M_PI/4.0);
    [view addSubview:label];
    
    
    UIGraphicsBeginImageContextWithOptions(view.bounds.size, NO, [UIScreen mainScreen].scale);
    [view.layer renderInContext:UIGraphicsGetCurrentContext()];
    UIImage *image=UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    
    return image;
}