给图片画文字

- (UIImage *)createShareImage:(NSString *)imageName Context:(NSString *)text
{
    UIImage *sourceImage = [UIImage imageNamed:imageName];
    CGSize imageSize; //画的背景 大小
    imageSize = [sourceImage size];
    UIGraphicsBeginImageContextWithOptions(imageSize, NO, 0.0);
    [sourceImage drawAtPoint:CGPointMake(0, 0)];
    //获得 图形上下文
    CGContextRef context=UIGraphicsGetCurrentContext();
    CGContextDrawPath(context, kCGPathStroke);
    CGFloat nameFont = 20.f;
    //画 自己想要画的内容
    NSDictionary *attributes = @{NSFontAttributeName:[UIFont systemFontOfSize:nameFont]};
    CGRect sizeToFit = [text boundingRectWithSize:CGSizeMake(CGFLOAT_MAX, nameFont) options:NSStringDrawingUsesDeviceMetrics attributes:attributes context:nil];
    NSLog(@"图片: %f %f",imageSize.width,imageSize.height);
    NSLog(@"sizeToFit: %f %f",sizeToFit.size.width,sizeToFit.size.height);
    CGContextSetFillColorWithColor(context, [UIColor blackColor].CGColor);
    [text drawAtPoint:CGPointMake((imageSize.width-sizeToFit.size.width)/2,0) withAttributes:@{NSFontAttributeName:[UIFont systemFontOfSize:nameFont]}];
    //返回绘制的新图形
    
    UIImage *newImage=UIGraphicsGetImageFromCurrentImageContext();
    
    UIGraphicsEndImageContext();
    return newImage;
}