I am using coredata so I need sort descriptors for my entities
For example, a Coordinate-entity has this class func:
class func sortDescriptors() -> Array<NSSortDescriptor>
{
return [NSSortDescriptor(key: "sequence", ascending: true)]
}
I am using this when doing fetch-requests to CoreData like this:
var request = NSFetchRequest(entityName: entityName)
request.sortDescriptors = T.sortDescriptors()
However, when I have an array of coordinates as a property on another coredata object, this is an NSSet (Ie unsorted)
To solve this, I am returning the coordinates like this:
return NSArray(array: coordinates!).sortedArrayUsingDescriptors(Coordinate.sortDescriptors()) as? Array<Coordinate>
Which feels ugly, to use an NSArray just to get the sortedArrayUsingDescriptors
-method. Is there a similar way to do this directly on a Swift-array, Ie Array<Coordinate>
by using sort descriptors?
Thank you!
Another approach to the nice extensions of Damien could be a multi-cast.
myArray = (myArray as NSArray).sortedArrayUsingDescriptors(tableView.sortDescriptors) as! Array
Original source: NSHipster
There is no built-in method for this, but you can add them using protocol extension:
extension MutableCollectionType where Index : RandomAccessIndexType, Generator.Element : AnyObject {
/// Sort `self` in-place using criteria stored in a NSSortDescriptors array
public mutating func sortInPlace(sortDescriptors theSortDescs: [NSSortDescriptor]) {
sortInPlace {
for sortDesc in theSortDescs {
switch sortDesc.compareObject($0, toObject: $1) {
case .OrderedAscending: return true
case .OrderedDescending: return false
case .OrderedSame: continue
}
}
return false
}
}
}
extension SequenceType where Generator.Element : AnyObject {
/// Return an `Array` containing the sorted elements of `source`
/// using criteria stored in a NSSortDescriptors array.
@warn_unused_result
public func sort(sortDescriptors theSortDescs: [NSSortDescriptor]) -> [Self.Generator.Element] {
return sort {
for sortDesc in theSortDescs {
switch sortDesc.compareObject($0, toObject: $1) {
case .OrderedAscending: return true
case .OrderedDescending: return false
case .OrderedSame: continue
}
}
return false
}
}
}
But note that this will work only when the array elements are classes, not structures, as NSSortDescriptor compareObject method requires arguments conforming to AnyObject
Swift 3 Version of @Darniel's answer
extension MutableCollection where Self : RandomAccessCollection {
/// Sort `self` in-place using criteria stored in a NSSortDescriptors array
public mutating func sort(sortDescriptors theSortDescs: [NSSortDescriptor]) {
sort { by:
for sortDesc in theSortDescs {
switch sortDesc.compare($0, to: $1) {
case .orderedAscending: return true
case .orderedDescending: return false
case .orderedSame: continue
}
}
return false
}
}
}
extension Sequence where Iterator.Element : AnyObject {
/// Return an `Array` containing the sorted elements of `source`
/// using criteria stored in a NSSortDescriptors array.
public func sorted(sortDescriptors theSortDescs: [NSSortDescriptor]) -> [Self.Iterator.Element] {
return sorted {
for sortDesc in theSortDescs {
switch sortDesc.compare($0, to: $1) {
case .orderedAscending: return true
case .orderedDescending: return false
case .orderedSame: continue
}
}
return false
}
}
}
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