Swift generic function sorting by object property

sortBtProperty.swift

func sortByProperty<T: NSObject>(array: [T], property: String, ascending: Bool) -> [T] {
    
    var sortedBooks = [T](array)
    
    sortedBooks.sort { element1, element2 in
        var value1: AnyObject! = ""
        var value2: AnyObject! = ""
        
        if element1.respondsToSelector(Selector(property)) {
            value1 = element1.valueForKey(property)
        }
        
        if element2.respondsToSelector(Selector(property)) {
            value2 = element2.valueForKey(property)
        }
        
        var result: NSComparisonResult = .OrderedSame
        
        if value1 as? String {
            let string1 = (value1 as String).bridgeToObjectiveC()
            let string2 = (value2 as String).bridgeToObjectiveC()
            result = string1.compare(string2)
        } else if value1 as? NSDate {
            result = (value1 as NSDate).compare((value2 as NSDate))
        } else if value1 as? NSNumber {
            result = (value1 as NSNumber).compare((value2 as NSNumber))
        }
        
        
        if ascending {
            if result == .OrderedAscending {
                return true
            }
            return false
        } else {
            if result == .OrderedAscending {
                return false
            }
            return true
        }
        
    }
    
    return sortedBooks
}