1、绘制手势截屏

• 具体实现代码见 GitHub 源码 QExtension

• QTouchClipView.h

      @interface QTouchClipView : UIView
  
      /**
       *  创建手势截屏视图控件，获取截屏结果
       *
       *  @param view     截取图片的视图控件
       *  @param result   手势截屏结果
       *
       *  @return 手势截屏视图控件
       */
      + (instancetype)q_touchClipViewWithView:(UIView *)view
                                   clipResult:(void (^)(UIImage * _Nullable image))result;
  
      @end

• QTouchClipView.m

      @interface QTouchClipView ()
  
      /// 截取图片的视图控件
      @property (nonatomic, strong) UIView *baseView;
  
      /// 滑动手势结果
      @property (nonatomic, copy) void (^resultBlock)(UIImage * _Nullable);
  
      /// 触摸开始结束点
      @property (nonatomic, assign) CGPoint startP;
      @property (nonatomic, assign) CGPoint endP;
  
      @end
  
      @implementation QTouchClipView
  
      /// 创建手势截屏视图控件，获取截屏结果
      + (instancetype)q_touchClipViewWithView:(UIView *)baseView
                                   clipResult:(void (^)(UIImage * _Nullable image))result {
  
          QTouchClipView *clipView = [[self alloc] initWithFrame:baseView.frame];
  
          clipView.baseView = baseView;
          clipView.resultBlock = result;
  
          return clipView;
      }
  
      /// 初始化
      - (instancetype)initWithFrame:(CGRect)frame {
  
          if (self = [super initWithFrame:frame]) {
              self.backgroundColor = [[UIColor blackColor] colorWithAlphaComponent:0.5];
          }
          return self;
      }
  
      /// 触摸开始
      - (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(nullable UIEvent *)event {
  
          // 获取触摸起始点位置
          CGPoint startPoint = [touches.anyObject locationInView:self];
          self.startP = startPoint;
      }
  
      /// 触摸移动
      - (void)touchesMoved:(NSSet<UITouch *> *)touches withEvent:(nullable UIEvent *)event {
  
          // 获取触摸点位置
          CGPoint touchPoint = [touches.anyObject locationInView:self];
          self.endP = touchPoint;
  
          // 刷新视图
          [self setNeedsDisplay];
      }
  
      /// 触摸结束
      - (void)touchesEnded:(NSSet<UITouch *> *)touches withEvent:(nullable UIEvent *)event {
  
          // 截取屏幕图片
          UIGraphicsBeginImageContextWithOptions(self.baseView.bounds.size, NO, 0);
  
          CGContextRef ctx = UIGraphicsGetCurrentContext();
          [self.baseView.layer renderInContext:ctx];
  
          UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
  
          UIGraphicsEndImageContext();
  
          // 切割图片
          CGFloat x = self.startP.x;
          CGFloat y = self.startP.y;
          CGFloat w = self.endP.x - x;
          CGFloat h = self.endP.y - y;
  
          CGRect cutRect = CGRectMake(x * 2, y * 2, w * 2, h * 2);
  
          CGImageRef cgImage = CGImageCreateWithImageInRect(image.CGImage, cutRect);
          UIImage *newImage = [[UIImage alloc] initWithCGImage:cgImage];
          CGImageRelease(cgImage);
  
          // 返回截取结果
          if (self.resultBlock) {
              self.resultBlock(newImage);
          }
  
          // 移除截取视图控件
          [self removeFromSuperview];
          self.startP = CGPointZero;
          self.endP = CGPointZero;
  
          // 刷新视图
          [self setNeedsDisplay];
      }
  
      /// 触摸取消
      - (void)touchesCancelled:(NSSet *)touches withEvent:(nullable UIEvent *)event {
          [self touchesEnded:touches withEvent:event];
      }
  
      /// 绘制触摸区域
      - (void)drawRect:(CGRect)rect {
  
          CGFloat x = self.startP.x;
          CGFloat y = self.startP.y;
          CGFloat w = self.endP.x - x;
          CGFloat h = self.endP.y - y;
  
          CGRect clipRect = CGRectMake(x, y, w, h);
  
          UIBezierPath *path = [UIBezierPath bezierPathWithRect:clipRect];
          [[[UIColor whiteColor] colorWithAlphaComponent:0.2] setFill];
          [path fill];
      }
  
      @end

• ViewController.m

      // 创建手势截屏视图
      QTouchClipView *touchClipView = [QTouchClipView q_touchClipViewWithView:self.imageView
                                                                   clipResult:^(UIImage * _Nullable image) {
  
          // 获取处理截屏结果
          if (image) {
              UIImageWriteToSavedPhotosAlbum(image, self, @selector(image:didFinishSavingWithError:contextInfo:), nil);
          }
      }];
  
      // 添加手势截屏视图
      [self.view addSubview:touchClipView];

• 效果