addText 函数

-(UIImage *)addText:(UIImage *)img text:(NSString *)text1  {      //get image width and height      int w = img.size.width;      int h = img.size.height;      CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();      //create a graphic context with CGBitmapContextCreate      CGContextRef context = CGBitmapContextCreate(NULL, w, h, 8, 4 * w, colorSpace, kCGImageAlphaPremultipliedFirst);      CGContextDrawImage(context, CGRectMake(0, 0, w, h), img.CGImage);      CGContextSetRGBFillColor(context, 0.0, 1.0, 1.0, 1);      char* text = (char *)[text1 cStringUsingEncoding:NSASCIIStringEncoding];      CGContextSelectFont(context, "Georgia", 30, kCGEncodingMacRoman);      CGContextSetTextDrawingMode(context, kCGTextFill);      CGContextSetRGBFillColor(context, 255, 0, 0, 1);      CGContextSetTextMatrix(context, CGAffineTransformMakeRotation( -M_PI/4 ));      CGContextShowTextAtPoint(context, 60, 390, text, strlen(text));      //Create image ref from the context      CGImageRef imageMasked = CGBitmapContextCreateImage(context);      CGContextRelease(context);      CGColorSpaceRelease(colorSpace);      return [UIImage imageWithCGImage:imageMasked];    }