如何对包含可选NSdate的选项数组进行排序？
class HistoryItem {
var dateCompleted: NSDate?
}
let firstListObject = someListOfObject.last
let secondListObject = someOtherListOfObject.last
let thirdListObject = evenSomeOtherListOfObject.last //Last returns 'T?'
var array = [firstListObject,secondListObject,thirdListObject]
如何根据dateCompleted对数组进行排序？
您的排序功能可以使用可选链接和零的组合
合并运算符：
合并运算符：
sort(&array) {
(item1,item2) -> Bool in
let t1 = item1?.dateCompleted ?? NSDate.distantPast() as! NSDate
let t2 = item2?.dateCompleted ?? NSDate.distantPast() as! NSDate
return t1.compare(t2) == NSComparisonResult.OrderedAscending
}
这会对dateCompleted值上的项以及所有项进行排序
是nil,dateCompleted == nil的项目被视为“在遥远的过去”
这样他们就可以在所有其他物品之前订购.
更新Swift 3(假设dateCompleted是一个日期)：
array.sort { (item1,item2) -> Bool in
let t1 = item1?.dateCompleted ?? Date.distantPast
let t2 = item2?.dateCompleted ?? Date.distantPast
return t1 < t2
}
