将View转换为Image保持高清

• (UIImage *)transformToImage
  {
  CGSize selfSize = self.frame.size;
  if ([self isKindOfClass:[UIScrollView class]]) {
  UIScrollView scrollView = (UIScrollView )self;
  selfSize = scrollView.contentSize;
  }

  if (selfSize.width == 0 || selfSize.height == 0) {
  return nil;
  }

  UIGraphicsBeginImageContextWithOptions(selfSize, NO, [UIScreen mainScreen].scale);
  CGContextRef context = UIGraphicsGetCurrentContext();

  if ([self isKindOfClass:[UIScrollView class]]) {
  UIView *contentView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, selfSize.width, selfSize.height)];
  [self.subviews enumerateObjectsUsingBlock:^(__kindof UIView * _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
  [contentView addSubview:obj];
  }];
  [contentView.layer renderInContext:context];
  [contentView.subviews enumerateObjectsUsingBlock:^(__kindof UIView * _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
  [self addSubview:obj];
  }];
  } else {
  [self.layer renderInContext:context];
  }

  UIImage *resultImage = UIGraphicsGetImageFromCurrentImageContext();
  UIGraphicsEndImageContext();

  return resultImage;
  }

//解决两张图片合并模糊问题，放大倍数
UIImage * image1 = qrImageView.image;
UIImage * image2 = [UIImage imageNamed:@”Artboard.png”];
CGSize size = CGSizeMake(qrImageView.frame.size.width *3, qrImageView.frame.size.height *3);
UIGraphicsBeginImageContext(size);
[image1 drawInRect:CGRectMake(0, 0, size.width, size.height)];
[image2 drawInRect:CGRectMake(30 * 3, 30 * 3, size.width - 60 * 3, size.height - 60 * 3)];
UIImage *resultingImage = UIGraphicsGetImageFromCurrentImageContext();
qrImageView.image = resultingImage;
UIGraphicsEndImageContext();