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Use delegate in Swift

Last updated at 2016-01-14Posted at 2016-01-13

1 declare a protocol in Class A:

protocol ScrollerBarDelegate: NSObjectProtocol {
    func buttonAtIndexPressed(index: NSInteger)
}

2 decalre a property member in Class A:

Warning: There must be a weak before the property member!!!otherwise, there will be a retain cycle problem.

weak var delegate  : ScrollerBarDelegate?

3 find the place in Class A where you want to trigger the delegate function.

// 按钮触发方法
func funcBtnPressed(sender: UIButton) {
        funcIndex = sender.tag - 1991
        self.delegate?.buttonAtIndexPressed(funcIndex!)
    }

4 conform to Protocol in Class B.

class NewsViewController: UIViewController, ScrollerBarDelegate {
	//
}

5 set the object's delegate in Class B:

bar!.delegate = self

6 complete the function in delegate in Class B:

// MARK: - 协议方法
    func buttonAtIndexPressed(index: NSInteger) {
        //
        print(index)
    }