SwiftUI:如何阻止文本字段中的某些字符? [英] SwiftUI: How to block certain characters in a textfield?

问题描述

我的应用中有一个 url 地址栏，它只加载www.google.com"这种格式的 url；而不是https://www.google.com"

i have a url address bar in my app that only loads urls in this format "www.google.com" instead of "https://www.google.com"

@State private var text = ""
@State private var site = "www.google.com/"

    TextField("Enter a URL", text: $text, onCommit: {
            guard !text.isEmpty else {return}
            site = text
        })

我希望文本字段屏蔽这些字符https://"；这样每当用户从另一个浏览器复制和粘贴网址时，他们就不必手动删除https://"每次.

I want the Textfield to block out these characters "https://" so that whenever a user copies and pastes a url from another browser, they don't have to manually delete "https://" every time.

推荐答案

你可以试试这样的:

    struct ContentView: View {
    @State var txt = ""
    
    var body: some View {
        TextField("Enter Url", text: Binding(
            get: { txt },
            set: { newValue in
                if trim(newValue).starts(with: "https://") {
                    txt = String(trim(newValue).dropFirst(8))
                } else {
                    txt = newValue
                }
            }
        ))
    }
    
    func trim(_ str: String) -> String {
        return str.trimmingCharacters(in: .whitespacesAndNewlines)
    }
}

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