开始先引入UIKit框架

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    [self waterImage];
    [self clearUpImage];
    
}
/** 刮刮乐 */
- (void)clearUpImage{
    //图片透明
    //添加图片
    UIImageView *v2 = [[UIImageView alloc]initWithImage:[UIImage imageNamed:@"2.jpg"]];
    v2.frame = self.view.frame;
    [self.view addSubview:v2];
    
    UIImageView *v1 = [[UIImageView alloc]initWithImage:[UIImage imageNamed:@"1.jpg"]];
    v1.frame = self.view.frame;
    [self.view addSubview:v1];
    
    //添加手势
    UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc]initWithTarget:self action:@selector(panAction:)];
    [v1 addGestureRecognizer:pan];
    v1.userInteractionEnabled = YES;
}
- (void)panAction:(UIGestureRecognizer *)sender{
   //获取当前点
    CGPoint currentPoint = [sender locationInView:sender.view];
    //设置擦除范围
    CGFloat w = 50;
    CGRect clearR = CGRectMake(currentPoint.x - w / 2, currentPoint.y - w / 2, w, w);
    //开启图片上下文
     UIGraphicsBeginImageContextWithOptions(sender.view.frame.size, NO, 0);
    //获取上下文
    CGContextRef ctx = UIGraphicsGetCurrentContext();
    //将图片提交给上下文
    [sender.view.layer renderInContext:ctx];
    //擦除
    CGContextClearRect(ctx, clearR);
    //获取擦除后的图片
    UIImage *i = UIGraphicsGetImageFromCurrentImageContext();
    
    //赋值
    UIImageView *imv = (UIImageView *)sender.view;
    imv.image = i;
    //结束上下文
    UIGraphicsEndImageContext();
  

}
/** 图片打水印 */
- (void)waterImage{
    //获取图片
    UIImage *image = [UIImage imageNamed:@"1.jpg"];
    //开启图形上下文
    UIGraphicsBeginImageContextWithOptions(image.size, NO, 0);
    //绘制图片
    [image drawAtPoint:CGPointZero];
    //准备水印内容
    
    //文字
    NSString *str = @"爽爽出品";
    NSMutableDictionary *dict = [NSMutableDictionary dictionary];//改写字体属性
    dict[NSFontAttributeName] = [UIFont systemFontOfSize:30];//字号
    dict[NSForegroundColorAttributeName] = [UIColor blueColor];//颜色
    dict[NSStrokeWidthAttributeName] = @5;//空心
    [str drawInRect:CGRectMake(250, 380, 200, 50) withAttributes:dict];
    //图片
    UIImage *star = [UIImage imageNamed:@"star_faved"];
    [star drawInRect:CGRectMake(200, 380, 50, 50)];
    //生成一个新图片
    UIImage *i = UIGraphicsGetImageFromCurrentImageContext();
    UIImageView *imv = [[UIImageView alloc]initWithImage:i];
    imv.frame = self.view.frame;
    [self.view addSubview:imv];

}
@end