iOS 獲取要在 UIButton 中設置的默認 UISearchBar 圖標

Question

我試圖在另一個 UIButton 中設置默認的 UISearchBar 圖標（放大鏡）。

PS：我不想使用從某個地方下載的 png 我想使用默認的。

func 添加帶有自定義圖像的按鈕只是為了顯示一些示例：

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 中：

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

Answer 2

為 Swift 3 更新

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 擴展來獲取應用程序中任何位置的系統圖標。

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
    }
}

這是我們如何使用它的示例：

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