iOS 获取要在 UIButton 中设置的默认 UISearchBar 图标

Question

我正在尝试获取默认的 UISearchBar 图标（放大镜）以在另一个 UIButton 中设置。

PS: 我不想使用从某个地方下载的 png 我想使用默认的。

使用自定义图像添加按钮的功能只是为了展示一些示例：

func addRightNavigationButton(){
    let buttonBack: UIButton = UIButton.buttonWithType(UIButtonType.Custom) as! UIButton
    buttonBack.frame = CGRectMake(0, 0, 30, 33)
    buttonBack.setImage(UIImage(named:"search.png"), forState: UIControlState.Normal)
    buttonBack.addTarget(self, action: "barButtonItemClicked:", forControlEvents: UIControlEvents.TouchUpInside)
    var rightBarButtonItem: UIBarButtonItem = UIBarButtonItem(customView: buttonBack)
    self.navigationItem.setRightBarButtonItem(rightBarButtonItem, animated: false)
}

Answer 1

在Objective-C中：

UIBarButtonItem *searchItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemSearch target:self action:@selector(searchButtonItemClicked:)];
[self.navigationItem setRightBarButtonItem:searchItem animated:FALSE];

在Swift 1.2:

let searchItem : UIBarButtonItem = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.Search, target: self, action: "searchButtonItemClicked:")
self.navigationItem.rightBarButtonItem = searchItem;

Answer 2

更新 Swift 3

let searchBtn : UIBarButtonItem = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.search, target: self, action: #selector(self.searchFunction))
self.navigationItem.rightBarButtonItem = searchBtn;

Answer 3

您可以使用此 UIImage 扩展程序在应用程序的任何位置获取系统图标。

import UIKit

extension UIImage {

    public convenience init?(_ systemItem: UIBarButtonItem.SystemItem) {

        guard let sysImage = UIImage.imageFrom(systemItem: systemItem)?.cgImage else {
            return nil
        }

        self.init(cgImage: sysImage)
    }

    private class func imageFrom(systemItem: UIBarButtonItem.SystemItem) -> UIImage? {

        let sysBarButtonItem = UIBarButtonItem(barButtonSystemItem: systemItem, target: nil, action: nil)

        //MARK:- Adding barButton into tool bar and rendering it.
        let toolBar = UIToolbar()
        toolBar.setItems([sysBarButtonItem], animated: false)
        toolBar.snapshotView(afterScreenUpdates: true)

        if  let buttonView = sysBarButtonItem.value(forKey: "view") as? UIView{
            for subView in buttonView.subviews {
                if subView is UIButton {
                    let button = subView as! UIButton
                    let image = button.imageView!.image!
                    return image
                }
            }
        }
        return nil
    }
}

这是我们如何使用它的示例：

 let button = UIButton() ;
 let systemImage = UIImage(systemItem: UIBarButtonSystemItem.search) ;
 button.setImage(systemImage, for: .normal)

iOS 获取要在 UIButton 中设置的默认 UISearchBar 图标

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