在我的代码中,我正在返回一个[String]？包含存储在/ Documents / – 的文件名(lastPathComponent),按照上次修改的日期排序.
我相信我可能使用太多的步骤,并在这里寻找建议,如何减少代码.
为了达到目前所需的结果 – 我正在创建两个中间词典：var attributesDictionary：[String：AnyObject]？和var urlDictionary = [NSURL：NSDate]().循环通过初始[NSURL]我使用两个步骤 – .resourceValuesForKeys初始化attributesDictionary.然后填入urlDictionary,使其包含URL和NSURLContentModificationDateKey关键字的值.
我觉得应该有一种方法来实现这个结果,而不必创建urlDictionary和attributesDictionary,而不需要循环.也许从urlArray直接.这是我当前的代码：
编辑：Arthur Gevorkyan在第一条评论中指出,do {}不是必需的.
func getFileList() -> [String]? {
let directory = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory,inDomains: .UserDomainMask)[0]
let properties = [NSURLLocalizednameKey,NSURLCreationDateKey,NSURLContentModificationDateKey,NSURLLocalizedTypeDescriptionKey]
// no catch required - contentsOfDirectoryAtURL returns nil if there is an error
if let urlArray = try? NSFileManager.defaultManager().contentsOfDirectoryAtURL(directory,includingPropertiesForKeys: properties,options:NSDirectoryEnumerationoptions.SkipsHiddenFiles) {
var attributesDictionary: [String:AnyObject]?
var dateLastModified: NSDate
var urlDictionary = [NSURL:NSDate]()
for URLs in urlArray {
// no catch required - resourceValuesForKeys returns nil if there is an error
attributesDictionary = try? URLs.resourceValuesForKeys(properties)
dateLastModified = attributesDictionary?[NSURLContentModificationDateKey] as! NSDate
urlDictionary[URLs] = dateLastModified
}
// this approach to sort is used because NSDate cannot be directly compared with </>
return urlDictionary.filter{$0 != nil}.sort{$0.1.compare($1.1) == NSComparisonResult.OrderedDescending }.map{$0.0}.map{$0.lastPathComponent!}
} else {
return nil
}
}
可能的解决方案：
if let urlArray = try? NSFileManager.defaultManager().contentsOfDirectoryAtURL(directory,options:.SkipsHiddenFiles) {
return urlArray.map { url -> (String,NSTimeInterval) in
var lastModified : AnyObject?
_ = try? url.getResourceValue(&lastModified,forKey: NSURLContentModificationDateKey)
return (url.lastPathComponent!,lastModified?.timeIntervalSinceReferenceDate ?? 0)
}
.sort({ $0.1 > $1.1 }) // sort descending modification dates
.map { $0.0 } // extract file names
} else {
return nil
}
URL数组首先映射到(lastPathComponent,lastModificationDate)元组的数组,然后按照
最后修改日期,最后提取路径名.
attributesDictionary可以通过使用来避免
getResourceValue(_：forKey)仅检索最后一个修改日期.
Swift 3的更新：
let directory = FileManager.default.urls(for: .documentDirectory,in: .userDomainMask).first!
if let urlArray = try? FileManager.default.contentsOfDirectory(at: directory,includingPropertiesForKeys: [.contentModificationDateKey],options:.skipsHiddenFiles) {
return urlArray.map { url in
(url.lastPathComponent,(try? url.resourceValues(forKeys: [.contentModificationDateKey]))?.contentModificationDate ?? Date.distantPast)
}
.sorted(by: { $0.1 > $1.1 }) // sort descending modification dates
.map { $0.0 } // extract file names
} else {
return nil
}