UIGraphics 向图片上写字

相关的size自己设置一下就可以了

- ( UIImage *)createImageWithString:( NSString *)str
{
    CGSize textSize = [ NSString sizeWithText :str font :[ UIFont systemFontOfSize : 12.0 ] maxSize : CGSizeMake ( MAXFLOAT , 11 )];
   
    UIImage * image = [ UIImage imageNamed : @"ic_kehu_name" ];
    CGSize contextSize = CGSizeMake (textSize. width , 12 + 15 );
   
    // 开始图形上下文
    UIGraphicsBeginImageContextWithOptions (contextSize, NO , 0.0 );
   
    // 画图
    [image drawAtPoint : CGPointMake ((textSize. width / 2 ) - 6 , 15 )];
   
    // 获得一个位图图形上下文
    CGContextRef context = UIGraphicsGetCurrentContext ();
   
    CGContextDrawPath (context, kCGPathStroke );
   
    [str drawAtPoint : CGPointMake ( 0 , 0 ) withAttributes : @{ NSFontAttributeName : [ UIFont systemFontOfSize : 12.0 ], NSForegroundColorAttributeName :[ UIColor blackColor ] } ];
   
    // 返回绘制的新图形
    UIImage * newImage = UIGraphicsGetImageFromCurrentImageContext ();
   
    UIGraphicsEndImageContext ();
   
    return newImage;

}