我有一个通用控件类，需要根据视图控制器设置按钮的完成.由于setLeftButtonActionWithClosure函数需要将闭包作为参数，该闭包应设置为取消按钮的操作.既然我们需要将函数名作为字符串传递给action:parameter，那么在Swift中怎么可能呢.
func setLeftButtonActionWithClosure(completion: () -> Void)
{
self.leftButton.addTarget(<#target: AnyObject?#>, action: <#Selector#>, forControlEvents: <#UIControlEvents#>)
}
NOTE: like @EthanHuang said "This solution doesn't work if you have more than two instances. All actions will be overwrite by the last assignment."
如果要将闭包作为目标添加到UIButton，则必须使用extension将函数添加到UIButton类
Swift 5
import UIKit
extension UIButton {
private func actionHandler(action:(() -> Void)? = nil) {
struct __ { static var action :(() -> Void)? }
if action != nil { __.action = action }
else { __.action?() }
}
@objc private func triggerActionHandler() {
self.actionHandler()
}
func actionHandler(controlEvents control :UIControl.Event, ForAction action:@escaping () -> Void) {
self.actionHandler(action: action)
self.addTarget(self, action: #selector(triggerActionHandler), for: control)
}
}
Older
import UIKit
extension UIButton {
private func actionHandleBlock(action:(() -> Void)? = nil) {
struct __ {
static var action :(() -> Void)?
}
if action != nil {
__.action = action
} else {
__.action?()
}
}
@objc private func triggerActionHandleBlock() {
self.actionHandleBlock()
}
func actionHandle(controlEvents control :UIControlEvents, ForAction action:() -> Void) {
self.actionHandleBlock(action)
self.addTarget(self, action: "triggerActionHandleBlock", forControlEvents: control)
}
}
电话:
let button = UIButton()
button.actionHandle(controlEvents: .touchUpInside,
ForAction:{() -> Void in
print("Touch")
})