struct Test {
func isOk () -> Bool{
return true
}
var mapping: [Int: () -> Bool] = [
1: isOk
]
func test() -> Bool {
return mapping[1]()
}
}
我遇到了这个错误:
Cannot convert value of type '(Test) -> () -> Bool' to expected dictionary value type '() -> Bool'
有什么想法吗?谢谢!
最佳答案
你看到这个奇怪的类型 ((Test) -> () -> Bool
) 因为 Swift instance methods are curried functions .
如果将isOk
变成静态方法是可以接受的,你可以这样做:
struct Test {
static func isOk() -> Bool { //Make it static
return true
}
var mapping: [Int : () -> Bool] = [
1 : Test.isOk // Static method must be qualified by its parent type
]
func test() -> Bool { //Bool return value necessary
//TODO: remove force unwrapping.
return mapping[1]!() //subscripting a Dict might return nil
}
}
如果 isOk
必须保留为实例方法,您可以这样做:
struct Test {
func isOk() -> Bool {
return true
}
var mapping: [Int : (Test) -> () -> Bool] = [ //change type
1 : isOk
]
//the instance method received from the dict needs an instance to act on
func test(instance: Test) -> Bool { //Bool return value necessary
//TODO: remove force unwrapping.
return mapping[1]!(instance)() //curried function call
}
}
关于swift - 如何声明以函数为值并以整数为键的字典?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/38130377/