iOS系统层面绘制视图内容

正常绘制

• UIGraphicsBeginImageContext

  UIGraphicsBeginImageContext(self.view.bounds.size);
  [self.view drawViewHierarchyInRect:self.view.bounds afterScreenUpdates:YES];
  UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
  UIGraphicsEndImageContext();
  

绘制拓展

• UIGraphicsBeginImageContextWithOptions

  CGFloat scale = [UIScreen mainScreen].scale;
  UIGraphicsBeginImageContextWithOptions(self.view.bounds.size, NO, scale);
  [self.view drawViewHierarchyInRect:self.view.bounds afterScreenUpdates:YES];
  UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
  UIGraphicsEndImageContext();
  

补充

• 截取需要的部分视图

  UIImage *clipImage = [UIImage imageWithCGImage:CGImageCreateWithImageInRect(viewImage.CGImage, CGRectMake(x, y, w, h))];