如何使用Swift 3从Xib加载NSView

Posted 2021-03-27

如何从Xib正确加载NSView？

我的代码：

var topLevelArray: NSArray? = nil
let outputValue = AutoreleasingUnsafeMutablePointer<NSArray>(&topLevelArray)

if Bundle.main.loadNibNamed("RadioPlayerView", owner: nil, topLevelObjects: outputValue) {
    let views = outputValue.pointee
    return views.firstObject as! RadioPlayerView
}

topLevelArray = nil
return nil

问题是“outputValue”是一个自动释放指针，一旦我从函数返回，程序崩溃与ACCESS_BAD_ADDRESS

答案

我做了一个协议和扩展来做到这一点：

import Cocoa

protocol NibLoadable {
    static var nibName: String? { get }
    static func createFromNib(in bundle: Bundle) -> Self?
}

extension NibLoadable where Self: NSView {

    static var nibName: String? {
        return String(describing: Self.self)
    }

    static func createFromNib(in bundle: Bundle = Bundle.main) -> Self? {
        guard let nibName = nibName else { return nil }
        var topLevelArray: NSArray? = nil
        bundle.loadNibNamed(NSNib.Name(nibName), owner: self, topLevelObjects: &topLevelArray)
        guard let results = topLevelArray else { return nil }
        let views = Array<Any>(results).filter { $0 is Self }
        return views.last as? Self
    }
}

用法：

final class MyView: NSView, NibLoadable {
    // ...
}

//创建名为MyView.xib的xib

// ... 别的地方：

let myView: MyView? = MyView.createFromNib()