Question

获取数组中项目索引的最有效方法是什么？在Objective-C中，我们曾经能够做到：

[arrayName indexOfObject:myObject]

在Swift中，我知道我们可以做到以下几点。

index =arrayName.indexOf({$0 === myObject})

这是最干净，最有效的方法吗？

Answer 1

As Oliver pointed out, you can use

let index = array.indexOf(myObject)

However, this will only work if your object conforms to the Equatable protocol, to conform to it, you have to implement the == function, like this:

class MyClass {
}

extension MyClass: Equatable { }

func ==(lhs: MyClass, rhs: MyClass) -> Bool {
    return lhs === rhs // === returns true when both references point to the same object
}

If your class inherits from NSObject and your comparison is something other than just comparing pointers, you'll have to override isEqual: as well

override func isEqual(object: AnyObject?) -> Bool {
  guard let obj = object as? MyClass else { return false }
  return self == obj
}

Answer 2

You can use:

let index = array.indexOf(myObject)

You don't need to use the closure as indexOf accepts the element itself as an argument

Bear in mind that index is optional though

如何获取数组中项的索引？

2 个答案: