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[英]Cannot convert value of type '() -> Void' to expected argument type '(() -> Void)?'
[英]Cannot convert value of type 'Void' to expected argument type '(String) -> Void'
我正在編寫一個應用程序時出現此錯誤: Cannot convert value of type 'Void' to expected argument type '(String) -> Void'
function 是:
func updateSymbolsPadding(symbolType: String, symbolSize:inout Double) -> Void {
var size: Double
if symbolType=="multiply" {
size = 2.4
} else if symbolType=="circle" {
size = 2.0
} else if symbolType=="triangle" {
size = 2.0
} else if symbolType=="square" {
size = 2.0
} else if symbolType=="pentagon" {
size = 2.0
} else if symbolType=="octagon" {
size = 2.0
}
symbolSize = size
}
我在一個選擇器中把它叫回來:
Picker("symbol one", selection: $symbolOne, content: {
Image(systemName: "multiply")
.tag("multiply")
Image(systemName: "circle")
.tag("circle")
Image(systemName: "triangle")
.tag("triangle")
Image(systemName: "square")
.tag("square")
Image(systemName: "pentagon")
.tag("pentagon")
Image(systemName: "octagon")
.tag("octagon")
})
.onChange(of: symbolOne, perform: updateSymbolsPadding(symbolType: symbolOne, symbolSize: &symbolOneSize))
變量是:
@Binding var symbolOne: String
@Binding var symbolOneSize: Double
我該如何解決這個問題?
正如 Ptit Xav 所說:執行參數必須是一個閉包,而不是 function 調用的結果。
代替
.onChange(of: symbolOne, perform: updateSymbolsPadding(symbolType: symbolOne, symbolSize: &symbolOneSize))
和
.onChange(of: symbolOne) { symbolOne in
updateSymbolsPadding(symbolType: symbolOne, symbolSize: &symbolOneSize)
}
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