图片添加水印效果

//创建一个UIImage对象

UIImage *image = [UIImageimageNamed:@"scene1.jpg"];

//1.建立bitmap Context

UIGraphicsBeginImageContext(image.size);

//2.把原图绘制到context上

[imagedrawInRect:CGRectMake(0, 0, image.size.width, image.size.height)];

//3.把水印文字绘制到context上。

//在左下角加水印

CGRect textFrame =CGRectMake(0, image.size.height-40, 200, 40);

//设置水印文字属性

UIFont *font = [UIFontboldSystemFontOfSize:30];

NSMutableParagraphStyle*style = [[NSMutableParagraphStyle alloc] init];

style.alignment = NSTextAlignmentCenter;

UIColor *color = [UIColorcolorWithRed:254.0/255 green:201.0/255 blue:21.0/255 alpha:1];

[text drawInRect:textFramewithAttributes: @{NSFontAttributeName:font, NSForegroundColorAttributeName:color,NSParagraphStyleAttributeName:style}];

//4.从bitmap context上获取加了水印以后的图片。

UIImage *waterImage =UIGraphicsGetImageFromCurrentImageContext();

//5.关闭bitmap context。

UIGraphicsEndImageContext();

//6.返回获取的图片

return waterImage;

此方法最好独立成一个单独的类，只需一类方法就能完成。