ios - 在 Swift 中使用 isKindOfClass

Question

我正在尝试学习一些 Swift 语言，我想知道如何将以下 Objective-C 转换为 Swift:

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
    [super touchesBegan:touches withEvent:event];

    UITouch *touch = [touches anyObject];

    if ([touch.view isKindOfClass: UIPickerView.class]) {
      //your touch was in a uipickerview ... do whatever you have to do
    }
}

更具体地说，我需要知道如何在新语法中使用 isKindOfClass。

override func touchesBegan(touches: NSSet, withEvent event: UIEvent) {

    ???

    if ??? {
        // your touch was in a uipickerview ...

    }
}

Answer 1

正确的 Swift 运算符是是:

if touch.view is UIPickerView {
    // touch.view is of type UIPickerView
}

当然，如果你还需要给view赋值一个新的常量，那么if let ... as? ... 语法是你的男孩，正如凯文提到的那样。但如果您不需要该值而只需要检查类型，那么您应该使用 is 运算符。