ios - 如何使用setObject Swift 2.0实现基于时间的NSCache

我有一个缓存的NSDictionary。我需要实现一个带有时间戳的基于时间的setObject。 NSCache Class没有setExpiry。任何帮助，将不胜感激。

这是我到目前为止的扩展名:

import Foundation

extension NSCache {

class var sharedInstance : NSCache {
    struct Static {
        static let instance : NSCache = NSCache()
    }
    return Static.instance
 }
}

我在http://nshipster.com/nscache/中找到了NSCache Extension。有没有简单的时间戳到期方式实现？

extension NSCache {
subscript(key: AnyObject) -> AnyObject? {
    get {
        return objectForKey(key)
    }
    set {
        if let value: AnyObject = newValue {
            setObject(value, forKey: key)
        } else {
            removeObjectForKey(key)
        }
    }
 }
}

最佳答案

您还可以使用计时器清空队列:

private let ExpiringCacheObjectKey = "..."
private let ExpiringCacheDefaultTimeout: NSTimeInterval = 60

class ExpiringCache : NSCache {

    /// Add item to queue and manually set timeout
    ///
    /// - parameter obj: Object to be saved
    /// - parameter key: Key of object to be saved
    /// - parameter timeout: In how many seconds should the item be removed

    func setObject(obj: AnyObject, forKey key: AnyObject, timeout: NSTimeInterval) {
        super.setObject(obj, forKey: key)
        NSTimer.scheduledTimerWithTimeInterval(timeout, target: self, selector: "timerExpires:", userInfo: [ExpiringCacheObjectKey : key], repeats: false)
    }

    // Override default `setObject` to use some default timeout interval

    override func setObject(obj: AnyObject, forKey key: AnyObject) {
        setObject(obj, forKey: key, timeout: ExpiringCacheDefaultTimeout)
    }

    // method to remove item from cache

    func timerExpires(timer: NSTimer) {
        removeObjectForKey(timer.userInfo![ExpiringCacheObjectKey] as! String)
    }
}