Question

这是参考https://stackoverflow.com/a/47765972/8833459。以下陈述：

let fooPaths: [WritableKeyPathApplicator<Foo>] = [WritableKeyPathApplicator(\Foo.bar), WritableKeyPathApplicator(\Foo.baz)]

是否有一个init或其他可以做的事情，以便以下（或类似的东西）可能也有效？

let fooPaths: [WritableKeyPathApplicator<Foo>] = [\Foo.bar, \Foo.baz]

原始声明只是打字太多了！我的首选＆＃34;方法目前给出错误：

error: cannot convert value of type 'WritableKeyPath<Foo, String>' to expected element type 'WritableKeyPathApplicator<Foo>'

Answer 1

类型是不必要的：

let fooPaths = [WritableKeyPathApplicator(\Foo.bar), WritableKeyPathApplicator(\Foo.baz)]

第二个Foo是不必要的。

let fooPaths = [WritableKeyPathApplicator(\Foo.bar), WritableKeyPathApplicator(\.baz)]

如果您提供类型，也是第一个：

let fooPaths: [WritableKeyPathApplicator<Foo>] = [WritableKeyPathApplicator(\.bar),
                                                  WritableKeyPathApplicator(\.baz)]

如果主要关注的是输入，请添加本地类型：

typealias WKPA<T> = WritableKeyPathApplicator<T>
let fooPaths: [WKPA<Foo>] = [WKPA(\.bar),
                             WKPA(\.baz)]

如何简化Swift数组初始化

1 个答案: