转载：往UIImage上写字

//Add text to UIImage  
  
-(UIImage *)addText:(UIImage *)img text:(NSString *)text1{  
  
    int w = img.size.width;  
  
    int h = img.size.height;   
  
    //lon = h - lon;  
  
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();  
  
    CGContextRef context = CGBitmapContextCreate(NULL, w, h, 8, 4 * w, colorSpace, kCGImageAlphaPremultipliedFirst);  
  
      
    CGContextDrawImage(context, CGRectMake(0, 0, w, h), img.CGImage);  
  
    CGContextSetRGBFillColor(context, 0.0, 0.0, 1.0, 1);  
  
      
    char* text  = (char *)[text1 cStringUsingEncoding:NSASCIIStringEncoding];// "05/05/09";  
  
    CGContextSelectFont(context, "Arial", 18, kCGEncodingMacRoman);  
  
    CGContextSetTextDrawingMode(context, kCGTextFill);  
  
    CGContextSetRGBFillColor(context, 255, 255, 255, 1);  
  
      
   
    //rotate text  
  
    CGContextSetTextMatrix(context, CGAffineTransformMakeRotation( -M_PI/4 ));  
  
      
    CGContextShowTextAtPoint(context, 4, 52, text, strlen(text));  
  
      
      
    CGImageRef imageMasked = CGBitmapContextCreateImage(context);  
  
    CGContextRelease(context);  
  
    CGColorSpaceRelease(colorSpace);  
  
      
    return [UIImage imageWithCGImage:imageMasked];  
  
}  

 

 

第二种方法：

 

-(UIImage *)imageFromText:(NSString *)text{     UIFont *font = [UIFont systemFontOfSize:20.0];         
CGSize size  = [text sizeWithFont:font];     UIGraphicsBeginImageContext(size);     CGContextRef ctx = UIGraphicsGetCurrentContext();       
// optional: add a shadow      
 // optional: also, to avoid clipping you should make the context size bigger     CGContextSetShadowWithColor(ctx, CGSizeMake(2.0, -2.0), 5.0, [[UIColor grayColor] CGColor]);       
// draw in context       
[text drawAtPoint:CGPointMake(0.0, 0.0) withFont:font];      
// transfer image       
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();          
UIGraphicsEndImageContext();          
return image;  
}  

 

 

 

第三种方法：

 

UIImage *myImage = loadUnwatermarkedImage();   
NSString *myWatermarkText = @"Watermark";   
UIImage *watermarkedImage = nil;   
   
UIGraphicsBeginImageContext(myImage.size);   
[myImage drawAtPoint: CGPointZero];   
[myWatermarkText drawAtPoint: CGPointMake(10, 10) withFont: [UIFont systemFontOfSize: 12]];   
watermarkedImage = UIGraphicsGetImageFromCurrentImageContext();   
UIGraphicsEndImageContext();   

 

 

 

第四种方法:

 

UIGraphicsBeginImageContext([parentView bounds].size); [[parentView layer] renderInContext:UIGraphicsGetCurrentContext()];  
UIImage *outputImage = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext();