如何删除iOS 11上UISearchController下的行？

Question

如何删除iOS 11上UISearchController下的行？

我使用以下代码添加了UISearchController：

navigationItem.searchController = searchController

但在这之后，它下面有一条奇怪的线：

任何关于如何删除线条或至少选择其颜色的建议都将非常感激。

Answer 1

一个hacky解决方案，但我现在最好的解决方案是添加一条与暗线重叠的白线视图：

let lineView = UIView(frame: CGRect(x: 0, y: searchController.searchBar.frame.height-4, width: view.bounds.width, height: 1))
lineView.backgroundColor = .white
searchController.searchBar.addSubview(lineView)

Answer 2

这是另一种解决方案，虽然很弱，但是在特定的用例中可能会有用。

extension UISearchController {

    var hairlineView: UIView? {
        guard let barBackgroundView = self.searchBar.superview?.subviews.filter({ String(describing: type(of: $0)) == "_UIBarBackground" }).first
        else { return nil }

        return barBackgroundView.subviews.filter({ $0.bounds.height == 1 / self.traitCollection.displayScale }).first
    }
}

有了该扩展名，您只需在视图控制器的viewWillLayoutSubviews方法中编写以下代码：

override func viewWillLayoutSubviews() {
    super.viewWillLayoutSubviews()

    // Remove hairline from the searchBar.
    self.navigationItem.searchController?.hairlineView?.isHidden = true
}

---

重要提示：

请注意，此解决方案确实很弱，并且可能会随将来的iOS更新而中断。
此外，$0.bounds.height == 1 / self.traitCollection.displayScale是不安全的，我建议您使用a proper float comparison method。

Answer 3

如果将其添加为子视图，则在按后退或前进到另一页时会发现故障。这可以改善您的解决方案@budidino

let lineView = UIView(frame: .zero)
lineView.backgroundColor = .white
searchController.searchBar.addSubview(lineView)

lineView.translatesAutoresizingMaskIntoConstraints = false
lineView.leadingAnchor.constraint(equalTo: searchController.searchBar.leadingAnchor).isActive = true
lineView.trailingAnchor.constraint(equalTo: searchController.searchBar.trailingAnchor).isActive = true
lineView.bottomAnchor.constraint(equalTo: searchController.searchBar.bottomAnchor, constant: 1).isActive = true
lineView.heightAnchor.constraint(equalToConstant: 1).isActive = true

Answer 4

在iOS11中

@interface UISearchController (Additions)
- (void)hideHairLineView;
@end

@implementation UISearchController (Additions)
- (void)hideHairLineView{
    UIView *barBackgroundView = self.searchBar.superview.subviews.firstObject;
    for(UIView *v in barBackgroundView.subviews) {
        if ([v isKindOfClass:[UIImageView class]]) {
            UIImageView *imgView= (UIImageView *)v;
            if (imgView.frame.size.height <= 1.0) {
                [imgView setHidden:YES];
            }
        }
    }
}

在viewWillLayoutSubviews

- (void)viewWillLayoutSubviews {
    [super viewWillLayoutSubviews];
    [self.navigationItem.searchController hideHairLineView];
}

在iOS13中

来自viewDidLoad添加 [self.navigationController setDelegate:self];

#pragma mark - UINavigationControllerDelegate

- (void)navigationController:(UINavigationController *)navigationController willShowViewController:(UIViewController *)viewController animated:(BOOL)animated {
    [viewController.navigationController.navigationBar.viewForLastBaselineLayout setBackgroundColor:[UIColor clearColor]];
}