返回手势-函数声明了一个不透明的返回类型，但在其主体中没有可用于推断基础类型的返回语句

Question

尝试创建一个递增值的函数，然后返回longPress手势。接收以下

函数声明了一个不透明的返回类型，但没有返回语句在其体内，从中推断潜在类型

函数背后的原因是因为我有三个按钮，它们的增量为一。

struct CustomFoodItemView: View {
@State var foodName = ""
@State var proteinAmount = 1
@State var carbAmount = 1
@State var fatAmount = 1

@State private var timer: Timer?
@State var isLongPressing = false

var body: some View {

let releaseGesture = DragGesture(minimumDistance: 0) // << detects finger release
.onEnded { _ in
self.timer?.invalidate()
}

func longPressAction ( macroToIncrease: inout Int) -> some Gesture{
let longPressGesture = LongPressGesture(minimumDuration: 0.2)
.onEnded { _ in
self.timer = Timer.scheduledTimer(withTimeInterval: 0.1, repeats: true, block: { _ in
macroToIncrease += 1
})

}
return longPressGesture
}

let proteinCombined = longPressAction(macroToIncrease: &proteinAmount).sequenced(before: releaseGesture)

VStack{
VStack{
Text("Food Name")
TextField("", text: $foodName)
.multilineTextAlignment(.center)
.border(.white)
.padding(.trailing, 10)
.frame(width:100, height:10)
}
HStack{
Text(String(proteinAmount) + "g")
.frame(width:50, height:50)

Image(systemName: "plus.circle.fill")
.resizable()
.aspectRatio(contentMode: .fit)
.frame(width: 30, height: 30)
.foregroundColor(Color("SuccessButtonColor"))
.onTapGesture{
proteinAmount += 1
}
.gesture(proteinCombined)


Image(systemName: "minus.circle.fill")
.resizable()
.aspectRatio(contentMode: .fit)
.frame(width: 30, height: 30)
.foregroundColor(Color("SuccessButtonColor"))

}

}
}
Spacer()
.frame(maxWidth:.infinity, maxHeight: .infinity)

}
}

Answer 1

由于有多个let变量，视图不知道显示/返回什么。在外部VStack之前放置一个return来修复它。

然后去掉一些大括号并修复longPressAction函数。这应该有助于：https://www.hackingwithswift.com/books/ios-swiftui/how-to-use-gestures-in-swiftui.

固定代码：

struct CustomFoodItemView: View {
@State var foodName = ""
@State var proteinAmount = 1
@State var carbAmount = 1
@State var fatAmount = 1

@State private var timer: Timer?
@State var isLongPressing = false

var body: some View {
let releaseGesture = DragGesture(minimumDistance: 0) // << detects finger release
.onEnded { _ in
self.timer?.invalidate()
}

let longPressGesture = LongPressGesture(minimumDuration: 0.2)
.onEnded { _ in
self.timer = Timer.scheduledTimer(withTimeInterval: 0.1, repeats: true, block: { _ in
proteinAmount += 1
})
}

let proteinCombined = longPressGesture.sequenced(before: releaseGesture)

return VStack {
VStack {
Text("Food Name")
TextField("", text: $foodName)
.multilineTextAlignment(.center)
.border(.white)
.padding(.trailing, 10)
.frame(width: 100, height: 10)
}
HStack {
Text(String(proteinAmount) + "g")
.frame(width: 50, height: 50)

Image(systemName: "plus.circle.fill")
.resizable()
.aspectRatio(contentMode: .fit)
.frame(width: 30, height: 30)
.foregroundColor(Color("SuccessButtonColor"))
.onTapGesture {
proteinAmount += 1
}
.gesture(proteinCombined)

Image(systemName: "minus.circle.fill")
.resizable()
.aspectRatio(contentMode: .fit)
.frame(width: 30, height: 30)
.foregroundColor(Color("SuccessButtonColor"))
}

Spacer()
.frame(maxWidth: .infinity, maxHeight: .infinity)
}
}
}