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UIControl block call back
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| import UIKit | |
| extension UIControl { | |
| /// add handler for specific `UIControl.Event` | |
| func addEvent(_ event: UIControl.Event, handler: @escaping (UIControl) -> Void) { | |
| let holder = EventHandlerHolder(action: handler) | |
| retainHolder(holder, for: event) | |
| addTarget(holder, action: #selector(holder.invokeHandler), for: event) | |
| } | |
| /// remove all `handler` of specific `UIControl.Event` | |
| func removeHandlers(for event: UIControl.Event) { | |
| var dic = eventHolderDictionary | |
| let oldKeys = dic.keys | |
| .map(\.uintValue) | |
| .map(UIControl.Event.init(rawValue:)) | |
| let eventsToModify = oldKeys.filter { $0.contains(event) } + [event] | |
| eventsToModify.forEach { oldEvent in | |
| let oldKey = NSNumber(value: oldEvent.rawValue) | |
| let newEvent = oldEvent.subtracting(event) | |
| if newEvent.isEmpty { | |
| dic[oldKey]?.forEach({ holder in | |
| removeTarget(holder, action: #selector(holder.invokeHandler), for: oldEvent) | |
| }) | |
| dic[oldKey] = nil | |
| } else { | |
| dic[oldKey]?.forEach({ holder in | |
| removeTarget(holder, action: #selector(holder.invokeHandler), for: oldEvent) | |
| addTarget(holder, action: #selector(holder.invokeHandler), for: newEvent) | |
| }) | |
| let newKey = NSNumber(value: newEvent.rawValue) | |
| dic[newKey] = dic[oldKey] | |
| dic[oldKey] = nil | |
| } | |
| } | |
| eventHolderDictionary = dic | |
| } | |
| } | |
| private var eventHolderDictionaryKey: Void? | |
| extension UIControl { | |
| private func retainHolder(_ holder: EventHandlerHolder, for event: UIControl.Event) { | |
| let key = NSNumber(value: event.rawValue) | |
| var dic = eventHolderDictionary | |
| let holders = dic[key] ?? [] | |
| dic[key] = holders.union([holder]) | |
| eventHolderDictionary = dic | |
| } | |
| private var eventHolderDictionary: [NSNumber: Set<EventHandlerHolder>] { | |
| get { | |
| let obj = objc_getAssociatedObject(self, &eventHolderDictionaryKey) as? [NSNumber: Set<EventHandlerHolder>] | |
| return obj ?? [:] | |
| } | |
| set { | |
| objc_setAssociatedObject(self, &eventHolderDictionaryKey, newValue, .OBJC_ASSOCIATION_COPY_NONATOMIC) | |
| } | |
| } | |
| private final class EventHandlerHolder: NSObject { | |
| let action: (UIControl) -> Void | |
| init(action: @escaping (UIControl) -> Void) { | |
| self.action = action | |
| } | |
| @objc fileprivate func invokeHandler(sender: UIControl) { | |
| action(sender) | |
| } | |
| } | |
| } |
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