Quartz 2D 实例：Watermark

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UIImage+Watermark.h

#import <UIKit/UIKit.h>@interface UIImage (Watermark)- (UIImage *)watermarkImageWithText:(NSString *)text;@end

UIImage+Watermark.m

#import "UIImage+Watermark.h"@implementation UIImage (Watermark)- (UIImage *)watermarkImageWithText:(NSString *)text{    //1.取到上下文    UIGraphicsBeginImageContext(self.size);    //2.绘制图片    [self drawInRect:CGRectMake(0, 0, self.size.width, self.size.height)];    //3.绘制水印文字    CGRect textRect = CGRectMake(0, self.size.height - 30, self.size.width, 30);    NSMutableParagraphStyle *style = [[NSMutableParagraphStyle defaultParagraphStyle] mutableCopy];    style.alignment = NSTextAlignmentCenter;    NSDictionary *attr = @{                           NSFontAttributeName: [UIFont boldSystemFontOfSize:25],                           NSParagraphStyleAttributeName: style,                           NSForegroundColorAttributeName: [UIColor whiteColor]                           };//    [[UIColor whiteColor] set];    [text drawInRect:textRect withAttributes:attr];    //4.获取到绘制完成的图片    UIImage *watermarkedImage = UIGraphicsGetImageFromCurrentImageContext();    //5.结束在图片上的绘制    UIGraphicsEndImageContext();    return watermarkedImage;}@end

ViewController.m

#import "ViewController.h"#import "UIImage+Watermark.h"@interface ViewController ()@end@implementation ViewController- (void)viewDidLoad {    [super viewDidLoad];   //水印    UIImage *originImage = [UIImage imageNamed:@"屏幕快照 2015-04-04 16.21.17.png"];    UIImage *watermarkedImage = [originImage watermarkImageWithText:@"Mainning.blog"];    UIImageView *imgView = [[UIImageView alloc] initWithImage:watermarkedImage];    imgView.frame = self.view.bounds;    [self.view addSubview:imgView];}@end

这里写图片描述

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