如何以编程方式创建固定空间和灵活的空格键按钮项目？

Question

我想以编程方式创建 UIBarButtonItems 并将这些固定空间项目放置在按钮之间。

Answer 1

UIBarButtonItem *fixedItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFixedSpace target:nil action:nil];
fixedItem.width = 20.0f; // or whatever you want

UIBarButtonItem *flexibleItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace target:nil action:nil];

Answer 2

斯威夫特

// Fixed Space
let fixedSpace: UIBarButtonItem = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.FixedSpace, target: nil, action: nil)
fixedSpace.width = 20.0

// Flexible Space
let flexibleSpace: UIBarButtonItem = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.FlexibleSpace, target: nil, action: nil)

Answer 3

UIBarButtonItem *todayItem = [[UIBarButtonItem alloc] initWithTitle:@"Today" style:UIBarButtonItemStylePlain target:self action:@selector(update_baritem:)];
todayItem.tag = 2;

UIBarButtonItem *cashItem = [[UIBarButtonItem alloc] initWithTitle:@"Cash" style:UIBarButtonItemStylePlain target:self action:@selector(update_baritem:)];
cashItem.tag = 3;

UIBarButtonItem *creditItem = [[UIBarButtonItem alloc] initWithTitle:@"Credit" style:UIBarButtonItemStylePlain target:self action:@selector(update_baritem:)];
creditItem.tag = 4;

UIBarButtonItem *allItem = [[UIBarButtonItem alloc] initWithTitle:@"All" style:UIBarButtonItemStylePlain target:self action:@selector(update_baritem:)];
allItem.tag = 1;

UIBarButtonItem *returnItem = [[UIBarButtonItem alloc] initWithTitle:@"Return" style:UIBarButtonItemStylePlain target:self action:@selector(update_baritem:)];
returnItem.tag = 5;

UIBarButtonItem *fixedItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFixedSpace target:nil action:nil];
[fixedItem setWidth:455.0f];

UIBarButtonItem *fixed2Item = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFixedSpace target:nil action:nil];
[fixed2Item setWidth:37.0f];

UIBarButtonItem *flexibleItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace target:nil action:nil];

[self.toolbar setItems:@[fixed2Item, returnItem, creditItem, cashItem, fixedItem, todayItem, flexibleItem, allItem] animated:NO];

Answer 4

在撰写本文时，如果您的目标是 iOS 14 及更高版本，则可以使用相应的类函数更简洁地获取固定和灵活的空间项：

let fixedSpace = UIBarButtonItem.fixedSpace(20)
let flexibleSpace = UIBarButtonItem.flexibleSpace()

文档：固定空间, 灵活空间

Answer 5

在斯威夫特：

let fixedSpace = UIBarButtonItem(barButtonSystemItem: .fixedSpace, target: nil, action: nil)
fixedSpace.width = 20.0

Answer 6

斯威夫特5.1.2

// Fixed Space
let fixedSpace: UIBarButtonItem = UIBarButtonItem(barButtonSystemItem: .fixedSpace, target: nil, action: nil)
fixedSpace.width = 20.0

// Flexible Space
let flexibleSpace: UIBarButtonItem = UIBarButtonItem(barButtonSystemItem: .flexibleSpace, target: nil, action: nil)

Answer 7

在 ViewDidLoad 中：

    //toolbar
UIToolbar *toolBar = [[UIToolbar alloc] initWithFrame:CGRectMake(0, 416, 320, 44)];

// bar btns
UIBarButtonItem *backBtn = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemRewind target:self action:@selector(goBack)];
UIBarButtonItem *forwardBtn = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFastForward target:self action:@selector(goForward)];
UIBarButtonItem *flexibleSpace = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace target:self action:nil];
UIBarButtonItem *bookmarkBtn = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemBookmarks target:self action:@selector(bookmark)];
UIBarButtonItem *refreshBtn = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemRefresh target:self action:@selector(refresh)];
UIBarButtonItem *stopLoadingBtn = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemStop target:self action:@selector(stopLoading)];

// add btns to the bar
[toolBar setItems:[NSMutableArray arrayWithObjects:bookmarkBtn,backBtn,forwardBtn,flexibleSpace,refreshBtn,stopLoadingBtn, nil]];

// adds the toobar to the view
[self.view addSubview:toolBar];

也不要忘记每个按钮的操作（在本例中为 UIWebView）：

    -(void)goBack
{
    [_webView goBack];
}

-(void)goForward
{
    [_webView goForward];
}

等等。

Answer 8

在 Swift 3 中，UIBarButtonItem 有一个名为 init(barButtonSystemItem:target:action:)。 init(barButtonSystemItem:target:action:) 具有以下声明：

convenience init(barButtonSystemItem systemItem: UIBarButtonSystemItem, target: Any?, action: Selector?)

初始化包含指定系统项目的新项目。

---

UIBarButtonSystemItem 是一个枚举，提供了许多情况，包括 完成、播放、添加或取消。不过，根据您的需要，您也可以选择flexibleSpace或fixedSpace案例。

flexibleSpace 案例具有以下声明：

在其他项目之间添加空格。空间在其他项目之间平均分配。设置此值后，其他项目属性将被忽略。

fixedSpace 案例具有以下声明：

在其他项目之间添加空格。设置此值时，仅使用 width 属性。

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因此，您可以通过编程方式创建固定和灵活的空格键项目，如下所示：

let flexibleSpace = UIBarButtonItem(
    barButtonSystemItem: UIBarButtonSystemItem.flexibleSpace,
    target: nil,
    action: nil
)

let fixedSpace = UIBarButtonItem(
    barButtonSystemItem: UIBarButtonSystemItem.fixedSpace,
    target: nil,
    action: nil
)
fixedSpace.width = 30 // Set width with the appropriate value

---

作为示例，下面的 Playground 代码展示了如何添加一个底部栏，其中两个居中的播放和暂停栏按钮项目以 30 的固定间距分隔开。视图控制器：

import PlaygroundSupport
import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        view.backgroundColor = .white
        title = "Home"
    }

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)

        // Show navigation controller’s built-in toolbar
        navigationController?.setToolbarHidden(false, animated: false)

        // Create UIBarButtonItems
        let flexibleSpace1 = UIBarButtonItem(barButtonSystemItem: .flexibleSpace, target: nil, action: nil)
        let playItem = UIBarButtonItem(barButtonSystemItem: .play, target: self, action: nil)
        let fixedSpace = UIBarButtonItem(barButtonSystemItem: .fixedSpace, target: nil, action: nil)
        fixedSpace.width = 30
        let pauseItem = UIBarButtonItem(barButtonSystemItem: .pause, target: self, action: nil)
        let flexibleSpace2 = UIBarButtonItem(barButtonSystemItem: .flexibleSpace, target: nil, action: nil)

        // Set the view controller toolbar items
        setToolbarItems([flexibleSpace1, playItem, fixedSpace, pauseItem, flexibleSpace2], animated: false)
    }

    override func viewWillDisappear(_ animated: Bool) {
        // Hide navigation controller’s built-in toolbar
        navigationController?.setToolbarHidden(true, animated: true)

        super.viewWillDisappear(animated)
    }

}

let viewController = ViewController()
let navigationController = UINavigationController(rootViewController: viewController)
PlaygroundPage.current.liveView = navigationController

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使用 View 在 Playground 助理编辑器中预览视图控制器 ▸ 助理编辑器 ▸ 显示助理编辑器