我正在直接从Parse中提取一系列字典并将它们显示在表格中.所以我真的很想处理我所掌握的数据结构(下面奇怪的结构化词典).
PFObject是[String：AnyObject？],我希望能够按任意键排序,因此我不知道对象类型,并且某些字典可能缺少键.因为在Parse中,如果不给属性赋值,则它根本就不存在.例如：
[
{
"ObjectId" : "1","Name" : "Frank","Age" : 32
},{
"ObjectId" : "2","Name" : "Bill"
},{
"ObjectId" : "3","Age" : 18
}
{
"ObjectId" : "4","Name" : "Susan","Age" : 47
}
]
我希望在排序的词典之后始终按顺序排列缺少键的词典.一个例子：
原表：
ObjectId Name Age 1 Frank 32 2 Bill 3 18 4 Susan 47
按名称排序：
ObjectId Name Age 2 Bill 1 Frank 32 4 Susan 47 3 18
由于我对数据模型没有太多控制权,并且它的使用在整个应用程序中受到限制,我更倾向于关注算法解决方案而不是结构化.
我想出了一个方法来做到这一点,但它似乎效率低而且速度慢,我确信有人可以做得更好.
//dataModel is an array of dictionary objects used as my table source
//sort mode is NSComparisonResult ascending or descending
//propertyName is the dictionary key
//first filter out any objects that dont have this key
let filteredFirstHalf = dataModel.filter({ $0[propertyName] != nil })
let filteredSecondHalf = dataModel.filter({ $0[propertyName] == nil })
//sort the dictionaries that have the key
let sortedAndFiltered = filteredFirstHalf { some1,some2 in
if let one = some1[propertyName] as? NSDate,two = some2[propertyName] as? NSDate {
return one.compare(two) == sortMode
} else if let one = some1[propertyName] as? String,two = some2[propertyName] as? String {
return one.compare(two) == sortMode
} else if let one = some1[propertyName] as? NSNumber,two = some2[propertyName] as? NSNumber {
return one.compare(two) == sortMode
} else {
fatalError("filteredFirstHalf shouldn't be here")
}
}
//this will always put the blanks behind the sorted
dataModel = sortedAndFiltered + filteredSecondHalf
谢谢！
解决方法
Swift无法比较任何两个对象.您必须先将它们转换为特定类型：
let arr: [[String: Any]] = [
["Name" : "Frank","Age" : 32],["Name" : "Bill"],["Age" : 18],["Name" : "Susan","Age" : 47]
]
let key = "Name" // The key you want to sort by
let result = arr.sort {
switch ($0[key],$1[key]) {
case (nil,nil),(_,nil):
return true
case (nil,_):
return false
case let (lhs as String,rhs as String):
return lhs < rhs
case let (lhs as Int,rhs as Int):
return lhs < rhs
// Add more for Double,Date,etc.
default:
return true
}
}
print(result)
如果有多个字典没有指定键的值,它们将被放置在结果数组的末尾,但它们的相对顺序是不确定的.
