英文:
SwiftUI TextFields with Integer
问题
在SwiftUI中，我有两个文本字段。其中一个是String，另一个应该是Int。我希望在“保存”功能之前和之后文本字段都为空。
这是我声明Int变量的方式：
@State private var newItemDays: Int?
这是文本字段：
TextField("任务标题", text: $newItemTitle)
.padding()
.background(Color.white)
TextField("倒计时天数", value: $newItemDays, formatter: NumberFormatter())
.keyboardType(.numberPad)
.padding()
.background(Color.white)
我的"确定"按钮保存它们：
Button("确定") {
if let days = newItemDays {
let newItem = CountdownItem(title: newItemTitle, daysLeft: days)
self.store.add(item: newItem)
newItemTitle = ""
newItemDays = 0
isTextFieldVisible = false
}
}
if语句始终返回false，即使我输入了整数。如果我删除声明中的可选项并将其设置为0，它可以正常工作，但这时文本字段中会显示0（它应该为空）。
有什么帮助吗？
英文:
In SwiftUI, I have two textfields. One of them is String and the other should be Int. And I want textfields to appear empty before and after "save" functionality.
this is how I declare my Int variable
@State private var newItemDays: Int?
this is the textfields
TextField("Task Title", text: $newItemTitle)
.padding()
.background(Color.white)
TextField("Days to Countdown", value: $newItemDays, formatter: NumberFormatter())
.keyboardType(.numberPad)
.padding()
.background(Color.white)
And my Ok button saves them.
Button("OK") {
if let days = newItemDays {
let newItem = CountdownItem(title: newItemTitle, daysLeft: days)
self.store.add(item: newItem)
newItemTitle = ""
newItemDays = 0
isTextFieldVisible = false
}
}
If statement always return false even though I put integer there. If I remove optional from the declaration and make it equal to 0, it works but this time I see 0 at the textfields (it should appear empty)
Any help?
答案1
得分: 1
你可以创建一个自定义的 NumberFormatter 并将 zeroSymbol 设置为空字符串：
let formatter: NumberFormatter = {
let formatter = NumberFormatter()
formatter.zeroSymbol = ""
return formatter
}()
然后你的 TextField 变成：
TextField("Days to Countdown", value: $newItemDays, formatter: formatter)
英文:
You can create a custom NumberFormatter & set the zeroSymbol to be an empty String:
let formatter: NumberFormatter = {
let formatter = NumberFormatter()
formatter.zeroSymbol = ""
return formatter
}()
And your TextField becomes:
TextField("Days to Countdown", value: $newItemDays, formatter: formatter)
答案2
得分: 1
使用 format: 替代 formatter:
TextField("倒计时天数", value: $newItemDays, format: .number)
当 value 是 Int? 时，初始状态会为空。
顺便提一下，不应该在 body 内初始化对象，这会导致内存泄漏，最好使用值类型。
英文:
Use format: instead of formatter:
TextField("Days to Countdown", value: $newItemDays, format: .number)
When value is Int? it will appear empty initially.
By the way, you shouldn't init objects like NumberFormatter() inside body it is a memory leak, best stick to value types.
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