无法推断泛型参数'A‘(Swift 4、键和ReactiveKit框架从Swift 2迁移)

Question

伙计们！我正在尝试从Swift 2迁移到Swift 4，项目使用的是邦德和ReactiveKit框架。我有UISearchBar的分机。因此，我面临着一个从这里迁移的问题：

import UIKit
import Bond
import ReactiveKit

public extension UISearchBar {
    public var bnd_delegate: ProtocolProxy {
        return protocolProxy(for: UISearchBarDelegate.self, setter: NSSelectorFromString("setDelegate:"))
    }
}

public extension UISearchBar {

    public var bnd_text: DynamicSubject<UISearchBar, String?> {
        let dispatcher: (PublishSubject<Void, NoError>, UISearchBar, String) -> Void = { _ in }
        let selector = #selector(UISearchBarDelegate.searchBar(_:textDidChange:))

    return DynamicSubject(
        target: self,
        signal: bnd_delegate.signal(for: selector, dispatch: dispatcher),
        get: { $0.text },
        set: { $0.text = $1 }
        )
    }
}

我已经做了一些修改，并对此代码进行了修改：

import UIKit
import Bond
import ReactiveKit

public extension UISearchBar {
    public var delegate: ProtocolProxy {
    return protocolProxy(for: UISearchBarDelegate.self, setter: NSSelectorFromString("setDelegate:"))
}

public var text: DynamicSubject<String?> {
    let dispatcher: (PublishSubject<Void, NoError>, UISearchBar, String) -> Void = { _,_,_   in }
    let selector = #selector(UISearchBarDelegate.searchBar(_:textDidChange:))

    return DynamicSubject<String?>(
        target: self,
        signal: delegate.signal(for: selector, dispatch: dispatcher),
        get: { $0.text },
        set: { $0.text = $1 }
        )
    }
}

目前，我在使用DynamicSubject：无法推断泛型参数'A‘时出错。这很奇怪，因为我检查了我的“分派”作为值的值是什么：(for: Selector, dispatch: (PublishSubject< S, NoError>, A, B) -> R)。

我试过处理调度变量的数量，但一无所获。在我看来，Xcode在PublishSubject参数之后没有识别任何变量。

我想知道我做错了什么。

Answer 1

如果您曾经从ReactiveKit/Bond实现语法的旧版本迁移，下面是如何为您的UIKit反应性扩展进行迁移：

import UIKit
import Bond
import ReactiveKit

extension ReactiveExtensions where Base: UISearchBar {

    var delegate: ProtocolProxy {
        return base.protocolProxy(for: UISearchBarDelegate.self, setter: NSSelectorFromString("setDelegate:"))
    }

    var text: DynamicSubject<String?> {

        let selector = #selector(UISearchBarDelegate.searchBar(_:textDidChange:))
        let textChanged = delegate.signal(for: selector) { (subj: SafePublishSubject<Void>, _: UISearchBar, _: NSString) in
            subj.next(())
        }

        return dynamicSubject(
            signal: textChanged,
            get: { $0.text },
            set: { $0.text = $1 }
        )
    }
}

extension UISearchBar: BindableProtocol {

    public func bind(signal: SafeSignal<String?>) -> Disposable {
        return reactive.text.bind(signal: signal)
    }
}