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();