为图片添加文字

#import "UIImage+watermark.h"

#define RGB_COLOR(R,G,B)[UIColor colorWithRed:R/255.0 green:G/255.0 blue:B/255.0 alpha:1.0]

@implementation UIImage (watermark)

- (UIImage *)watermarkImageWithText:(NSString *)text{

    UIGraphicsBeginImageContext(self.size);//获取上下文

    //绘制图片

    [self drawInRect:CGRectMake(0,0, self.size.width,self.size.height)];

    CGRect rect = CGRectMake(0,self.size.height-20, self.size.width,20);

    //段落格式

    NSMutableParagraphStyle  * style =[[NSMutableParagraphStyledefaultParagraphStyle]mutableCopy];

    style.alignment = NSTextAlignmentCenter;

    int R = arc4random()%255;

    int G = arc4random()%255;

    int B = arc4random()%255;

    //文字属性

    NSDictionary *dic =@{

                          NSFontAttributeName:[UIFontboldSystemFontOfSize:15],

                          NSParagraphStyleAttributeName:style,

                          NSForegroundColorAttributeName:RGB_COLOR(R,G,B)};

    //将文字绘制上去

    [text drawInRect:rectwithAttributes:dic];

    //获取绘制到的图片

    UIImage *watermarkImage =UIGraphicsGetImageFromCurrentImageContext();

    //结束图片绘制

    UIGraphicsEndImageContext();

    return watermarkImage;

}