浅谈Xcode9 和iOS11适配和特性

但是在iOS11里面你会发现段头段尾又回来辣！改了各种新增的属性比如safeArea之类的一点用都没有，最后发现必须要把estimatedSectionHeaderHeight置0才变回去

3.在iOS11中，苹果开放了NFC(Near field communication)，怕也是其推广ApplePay的一种策略。
在使用近场通讯时，首先也要在info.plist配置NFCReaderUsageDescription 权限，案例步骤，如下：

iOS 11 Core NFC - any sample code?

4.如果您在Navigation上的titleView上添加searchBar，iOS11情况下可能有问题

- (void)resetSearchBar
{
  CGFloat leftButtonWidth = 35, rightButtonWidth = 75; // left padding right padding
  UIView *container = [[UIView alloc] initWithFrame:CGRectMake(0, 0, self.view.frame.size.width - leftButtonWidth - rightButtonWidth, 44)];

  self.searchBar.translatesAutoresizingMaskIntoConstraints = NO;
  [container addSubview:self.searchBar];

  CGFloat offset = (rightButtonWidth - leftButtonWidth) / 2;
  // 给searchBar添加约束
  [NSLayoutConstraint activateConstraints:@[
                       [self.searchBar.topAnchor constraintEqualToAnchor:container.topAnchor], // 顶部约束
                       [self.searchBar.leftAnchor constraintEqualToAnchor:container.leftAnchor constant:-25*ScreenScaleX], // 左边距约束
                       [self.searchBar.rightAnchor constraintEqualToAnchor:container.rightAnchor constant:0], // 右边距约束
                       [self.searchBar.bottomAnchor constraintEqualToAnchor:container.bottomAnchor], // 底部约束
                       [self.searchBar.centerXAnchor constraintEqualToAnchor:container.centerXAnchor constant:-offset], // 横向中心约束
                       //                       [self.searchBar.widthAnchor constraintEqualToAnchor:container.widthAnchor constant:width] // 宽度约束
                       ]];
  self.navigationItem.titleView = container; // 顶部导航搜索
}