ios - 如何快速创建过滤器数组

Question

如何在 swift 中创建过滤器变量或多个过滤器？例如:

let i2 = $0.bCondition == "nonac"
let i3 = $0.aCondition == "nonac"
let i4 = $0.cCondition == "nonac"
if <some condition>{
  let i5 = $0.vCondition == "nonac"
  let i6 = $0.mCondition == "nonac"
 }
final filter = i2+i3+i4+i6+i5

这就是我要找的，有没有可用的解决方案？请指导我找到合适的解决方案。

Answer 1

从外观上看，您不仅希望动态添加 过滤器，还希望动态评估 它们。为此，您可以使用闭包和声明对它们进行操作的一些运算符:

// Closure that takes no arguments and returns Bool
typealias Filter = () -> Bool

// Convenience operator to combine outputs of two filters with AND operator
func && (lhs: Filter, rhs: Filter) -> Filter {
    return {
        lhs() && rhs()
    }
}

// Convenience operator to combine outputs of two filters with OR operator
func || (lhs: Filter, rhs: Filter) -> Filter {
    return {
        lhs() || rhs()
    }
}

示例:

var foo = "Foo"
let bar = "Bar"
let qux = "Qux"

let filter1: Filter = { foo == "Foo" }
let filter2: Filter = { bar == "Bar" }
let filter3: Filter = { qux == "Qux" }
let compositeFilter = filter1 && filter2 && filter3
//                  ^-- Is this what you are looking for?

let before = compositeFilter()

foo = "FOO"

let after = compositeFilter()

print(before)   // true
print(after)    // false