30.怎样在Swift中添加运行时属性？

1.示例

import UIKit

var s_GofButtonTouchDownKey = "s_GofButtonTouchDownKey";
var s_GofButtonTouchUpKey = "s_GofButtonTouchUpKey";

extension UIControl
{
/// 按钮TouchDown
var gof_touchDown: GofBtnClickBlock? {
get{
let touchDown = objc_getAssociatedObject(self, &s_GofButtonTouchDownKey);
let dealTouchDown = unsafeBitCast(touchDown, GofBtnClickBlock.self);
return dealTouchDown;
}
set(touchDown)
{
let dealTouchDown: AnyObject = unsafeBitCast(touchDown, AnyObject.self);
objc_setAssociatedObject(self, &s_GofButtonTouchDownKey, dealTouchDown, .OBJC_ASSOCIATION_COPY);

self.removeTarget(self, action: #selector(onTouchDown(_:)), forControlEvents: .TouchDown);
self.addTarget(self, action: #selector(onTouchDown(_:)), forControlEvents: .TouchDown)
}
}

/// 按钮TouchUpInside
var gof_touchUpInside: GofBtnClickBlock? {
get{
let touchUp = objc_getAssociatedObject(self, &s_GofButtonTouchUpKey);
let dealTouchUp = unsafeBitCast(touchUp, GofBtnClickBlock.self);
return dealTouchUp;
}
set(touchUp)
{
let dealTouchUp: AnyObject = unsafeBitCast(touchUp, AnyObject.self);
objc_setAssociatedObject(self, &s_GofButtonTouchUpKey, dealTouchUp, .OBJC_ASSOCIATION_COPY);

self.removeTarget(self, action: #selector(onTouchUp(_:)), forControlEvents: .TouchUpInside);
self.addTarget(self, action: #selector(onTouchUp(_:)), forControlEvents: .TouchUpInside)
}
}

/**
按钮TouchDown事件处理

- parameter btn: 按钮
*/
func onTouchDown(btn: UIButton) -> Void
{
let touchDown = self.gof_touchDown;

if touchDown != nil
{
touchDown!(btn);
}

}

/**
按钮TouchUpInside事件处理

- parameter btn: 按钮
*/
func onTouchUp(btn: UIButton) -> Void
{
let touchUp = self.gof_touchUpInside;

if touchUp != nil
{
touchUp!(btn);
}
}
}

2.示例说明

AnyObject，

extension UIButton
{
/**
创建UIButton控件

- parameter title:       按钮标题
- parameter superView:   按钮父视图
- parameter constraints: 约束
- parameter touchup:     按钮点击事件

- returns: UIButton控件
*/
static func gof_buttonWithTitle(title: String?, superView: UIView?, constraints: GofConstraintMaker?, touchup: GofBtnClickBlock?) -> UIButton
{
let button = UIButton(type: .Custom);
if title != nil
{
button.setTitle(title, forState: .Normal);
button.titleLabel?.font = kTitleFont;
}

button.backgroundColor = kCColor;

if superView != nil
{
superView!.addSubview(button);

if constraints != nil
{
button.snp_makeConstraints(closure: { (make) in
constraints!(make);
})
}
}

if touchup != nil
{
button.gof_touchUpInside = touchup!;
}

return button;
}
}