我正在Playgound中实现导航栏下方的分段控件。
这似乎是一个经典问题,有人问过:
在UIBarPositioningDelegate
的文件中,它说,
UINavigationBarDelegate,UISearchBarDelegate和UIToolbarDelegate协议扩展了此协议,以允许在屏幕上定位这些条。
在UIBarPosition的文档中:
案例顶部
指定该栏位于其包含视图的顶部。
在UIToolbar.delegate的文档中:
当工具栏由导航控制器管理时,您可能无法设置委托。默认值为nil。
我目前的解决方案如下(注释掉的代码是为了参考和方便):
import UIKit
import PlaygroundSupport
class ViewController : UIViewController, UIToolbarDelegate
{
let toolbar : UIToolbar = {
let ret = UIToolbar()
let segmented = UISegmentedControl(items: ["Good", "Bad"])
let barItem = UIBarButtonItem(customView: segmented)
ret.setItems([barItem], animated: false)
return ret
}()
override func viewDidLoad() {
super.viewDidLoad()
view.addSubview(toolbar)
// toolbar.delegate = self
}
override func viewDidLayoutSubviews() {
toolbar.frame = CGRect(
x: 0,
y: navigationController?.navigationBar.frame.height ?? 0,
width: navigationController?.navigationBar.frame.width ?? 0,
height: 44
)
}
func position(for bar: UIBarPositioning) -> UIBarPosition {
return .topAttached
}
}
//class Toolbar : UIToolbar {
// override var barPosition: UIBarPosition {
// return .topAttached
// }
//}
let vc = ViewController()
vc.title = "Try"
vc.view.backgroundColor = .red
// Another way to add toolbar...
// let segmented = UISegmentedControl(items: ["Good", "Bad"])
// let barItem = UIBarButtonItem(customView: segmented)
// vc.toolbarItems = [barItem]
// Navigation Controller
let navVC = UINavigationController(navigationBarClass: UINavigationBar.self, toolbarClass: UIToolbar.self)
navVC.pushViewController(vc, animated: true)
navVC.preferredContentSize = CGSize(width: 375, height: 640)
// navVC.isToolbarHidden = false
// Page setup
PlaygroundPage.current.liveView = navVC
PlaygroundPage.current.needsIndefiniteExecution = true
如你所见,这不使用UIToolbarDelegate
。
在这种情况下,UIToolbarDelegate
(提供position(for:)
)如何发挥作用?既然我们可以随时定位(手动或使用自动布局),那么UIToolbarDelegate
的用例是什么?
@Leo Natan在the first question link above的回答提到了UIToolbarDelegate
,但似乎工具栏放在Interface Builder中。
此外,如果我们不在这里使用UIToolbarDelegate
,为什么我们不使用普通的UIView
而不是UIToolbar
?
试试这个
UIView *containerVw = [[UIView alloc] initWithFrame:CGRectMake(0, 64, 320, 60)];
containerVw.backgroundColor = UIColorFromRGB(0xffffff);
[self.view addSubview:containerVw];
UIView *bottomView = [[UIView alloc] initWithFrame:CGRectMake(0, 124, 320, 1)];
bottomView.backgroundColor = [UIColor grayColor];
[self.view addSubview:bottomView];
UISegmentedControl *sg = [[UISegmentedControl alloc] initWithItems:@[@"Good", @"Bad"]];
sg.frame = CGRectMake(10, 10, 300, 40);
[view addSubview:sg];
for (UIView *view in self.navigationController.navigationBar.subviews) {
for (UIView *subView in view.subviews) {
[subView isKindOfClass:[UIImageView class]];
subView.hidden = YES;
}
}