导航栏按钮项目 swift 的图像

Question

我想在 swift 的导航栏左侧显示图像。

我试过添加导航栏按钮项目并在那里设置图像。

问题是我必须使用非常小的图像才能很好地适应导航栏。 但是制作这么小的图像会导致像素化，尤其是在更大的手机 iPhone 6 和 6 Plus 上。

有没有办法使用高质量的图像，然后将框架设置为适合导航栏的范围？

我的尝试：

var image = UIImage(named: "Harp.png")

image = image?.imageWithRenderingMode(UIImageRenderingMode.AlwaysOriginal)

self.navigationItem.leftBarButtonItem = UIBarButtonItem(image: image, style: UIBarButtonItemStyle.Plain, target: nil, action: nil)
self.navigationItem.leftBarButtonItem.frame = CGRectMake(0, 0, 53, 31)
//image.frame = CGRectMake(0, 0, 53, 31)

我尝试先将框架放在图像上，然后再放在栏按钮项目上。 但这是抛出一个错误：

没有更多上下文，表达式类型不明确。

Answer 1

尝试这个

let button = UIButton(type: UIButtonType.Custom)
button.setImage(UIImage(named: "yourImageName.png"), forState: UIControlState.Normal)
button.addTarget(self, action:Selector("callMethod"), forControlEvents: UIControlEvents.TouchDragInside)
button.frame=CGRectMake(0, 0, 30, 30)
let barButton = UIBarButtonItem(customView: button)
self.navigationItem.leftBarButtonItems = [newBackButton,barButton]

对于 Swift 3

let button = UIButton.init(type: .custom)
button.setImage(UIImage.init(named: "yourImageName.png"), for: UIControlState.normal)
button.addTarget(self, action:#selector(ViewController.callMethod), for:.touchUpInside)
button.frame = CGRect.init(x: 0, y: 0, width: 30, height: 30) //CGRectMake(0, 0, 30, 30)
let barButton = UIBarButtonItem.init(customView: button)
            self.navigationItem.leftBarButtonItem = barButton

斯威夫特 4

let button = UIButton(type: UIButton.ButtonType.custom)
button.setImage(UIImage(named: "getstarted"), for: .normal)
button.addTarget(self, action:#selector(callMethod), for: .touchDragInside)
button.frame = CGRect(x: 0, y: 0, width: 30, height: 30)
let barButton = UIBarButtonItem(customView: button)
self.navigationItem.leftBarButtonItems = [barButton]

这是行动

@objc func callMethod() {   
    //do stuff here
 }

Answer 2

使用此代码：

self.navigationItem.leftBarButtonItem = nil

let button = UIButton(type: .custom)
button.setImage(UIImage (named: "ChatTab"), for: .normal)
button.frame = CGRect(x: 0.0, y: 0.0, width: 35.0, height: 35.0)
//button.addTarget(target, action: nil, for: .touchUpInside)
let barButtonItem = UIBarButtonItem(customView: button)

let button2 = UIButton(type: .custom)
button2.setImage(UIImage (named: "ActivityTab"), for: .normal)
button2.frame = CGRect(x: 0.0, y: 0.0, width: 35.0, height: 35.0)
//button.addTarget(target, action: nil, for: .touchUpInside)

let barButtonItem2 = UIBarButtonItem(customView: button2)
self.navigationItem.rightBarButtonItems = [barButtonItem, barButtonItem2]

输出：

Answer 3

Swift 5、XCode 11 使用圆形图像、来自资产的图像或从 URL 下载的导航栏项目。

1) 新文件： UIBarButtonItem+RoundedView.swift

import Foundation

class ImageBarButton : UIView {
    var imageView: UIImageView!
    var button: UIButton!

    convenience init(withUrl imageURL: URL? = nil, withImage image: UIImage? = nil, frame: CGRect = CGRect(x: 0, y: 0, width: 40, height: 40)) {
        self.init(frame: frame)

        imageView = UIImageView(frame: frame)
        imageView.backgroundColor = .white
        imageView.layer.cornerRadius = frame.height/2
        imageView.clipsToBounds = true
        imageView.contentMode = .scaleAspectFill
        imageView.clipsToBounds = true
        addSubview(imageView)

        button = UIButton(frame: frame)
        button.backgroundColor = .clear
        button.setTitle("", for: .normal)
        addSubview(button)

        if let url = imageURL { // you can use pods like Nuke or Kingfisher 
         URLSession(configuration: .default).dataTask(with: URL(string: imageUrl)!) {[weak self] (data, response, error) in
          if let data = data , let image = UIImage(data: data) {
              DispatchQueue.main.async {
                self?.imgView.image = image
              }
           }
         }.resume()
        } else if let image = image {
            self.imageView.image = image
        }
    }

    func load()-> UIBarButtonItem {
        return UIBarButtonItem(customView: self)
    }
}

2) 添加导航栏项，可以使用navigationItem.rightBarButtonItems, navigationItem.leftBarButtonItems ：

private func initalizeNavigationBarItems() {
    let searchBarButtonView = ImageBarButton(withImage: #imageLiteral(resourceName: "greenSearchIcon")) // Assets
    searchBarButtonView.button.addTarget(self, action: #selector(presentSearchViewController), for: .touchUpInside)

    if let user = AccountManager.currentUser, let userProfilePictureURL = user.imageUrl { // API Url
        let profileBarButtonView = ImageBarButton(withUrl: userProfilePictureURL)
        profileBarButtonView.button.addTarget(self, action: #selector(presentMoreViewController), for: .touchUpInside)
        navigationItem.rightBarButtonItems = [searchBarButtonView.load(), profileBarButtonView.load()]
    } else {
        let profileBarButtonView = ImageBarButton(withImage: #imageLiteral(resourceName: "profileIcon"))
        profileBarButtonView.button.addTarget(self, action: #selector(presentMoreViewController), for: .touchUpInside)
        navigationItem.rightBarButtonItems = [searchBarButtonView.load(), profileBarButtonView.load()]
    }
}

@objc func presentMoreViewController(_ sender: Any) {
    // present MoreViewController
}

@objc func presentSearchViewController(_ sender: Any) {
    // present SearchViewController
}

预览

Answer 4

斯威夫特 4 和 5：

let imageView = UIImageView(image: UIImage(named: "Harp"))
let buttonItem = UIBarButtonItem(customView: imageView)
self.navigationItem.leftBarButtonItem = buttonItem

Answer 5

有一种方法可以使用不同大小的图像，具体取决于设备。 它被称为资产目录。 您的项目中可能已经有一个，如果没有，您可以使用File > New > File > Resource > Asset Catalogue添加一个。

在您的资产目录中，您可以拥有多个“图像集”（这些将显示在左侧）。 添加一个底部带有“+”的新图像集。 对于每个图像集，您可以为@1x、@2x 和@3x 中的每一个提供不同的图像（例如不同尺寸）。

然后，要在代码中使用这些图像之一，您只需使用UIImage(named: "name_of_image_set") - 注意没有扩展名。 将加载正确的图像，具体取决于设备。

希望这可以帮助！

Answer 6

Swift 5

您需要使用约束来正确设置带图像的导航栏按钮。

let button = UIButton(type: .custom)
button.setImage(UIImage(named: yourImageName), for: .normal)
button.translatesAutoresizingMaskIntoConstraints = false
button.widthAnchor.constraint(equalToConstant: 40).isActive = true
button.heightAnchor.constraint(equalToConstant: 40).isActive = true
let barButton = UIBarButtonItem(customView: button)
navigationItem.rightBarButtonItem = barButton