Conditionally activate UISearchController for iOS8+ - swift

Question

I have an app that I would like to target to iOS 7, but am currently unable to do so because it contains a UISearchController which is only available for iOS 8 and up.
I've been trying to modify the search bar with a UISearchDisplayController so that it works in iOS 7, but I just can't get it to work and am getting a little frustrated. So as a temporary measure (while I get better at coding), I would like to disable the search bar for any iOS below 8.0 - which won't impact the end user too much because its only one screen in a much larger app.
The problem is that I haven't been able to figure out how to do this conditionally (e.g., with "if #available(iOS 8.0, *)" ) because the variables "searchController" and "controller" are defined outside of a method or function and so can't be assigned conditionally. I guess conditional statements can only be used within functions and methods? (still learning, as you can see).
So can anyone offer a way for me to conditionally disable the search bar here so I can target iOS 7? My code for this class is below. Thanks!
class RegData2: UITableViewController, UISearchResultsUpdating {
let model = Model()
var prevArray = [String]()
var selectionPrev = String()
var filteredTableData = [String]()
var searchController = UISearchController()
let controller = UISearchController(searchResultsController: nil)
override func viewDidLoad() {
super.viewDidLoad()
self.searchController = ({
controller.searchResultsUpdater = self
controller.dimsBackgroundDuringPresentation = false
controller.searchBar.sizeToFit()
self.tableView.tableHeaderView = controller.searchBar
self.definesPresentationContext = true
return controller
})()
// Reload the table
self.tableView.reloadData()
}
override func numberOfSectionsInTableView(tableView: UITableView) -> Int {
return 1
}
override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
if (self.searchController.active) && (controller.searchBar.text != "") {
return self.filteredTableData.count
}
else {
return prevArray.count
}
}
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("cell") as UITableViewCell!
cell.textLabel?.font = UIFont.boldSystemFontOfSize(18)
if (self.searchController.active) && (controller.searchBar.text != "") {
cell.textLabel?.text = filteredTableData[indexPath.row]
return cell
}
else {
cell.textLabel?.text = prevArray[indexPath.row]
return cell
}
}
override func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath)
{
controller.searchBar.resignFirstResponder()
performSegueWithIdentifier("regData2ToRegView", sender: self)
}
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if segue.identifier == "regData2ToRegView" {
let regView = segue.destinationViewController as! RegView
let indexPath : NSIndexPath = self.tableView.indexPathForSelectedRow!
var selection : String = prevArray[indexPath.row]
if (self.searchController.active) && (self.controller.searchBar.text != "") {
selection = self.filteredTableData[indexPath.row]
}
else {
selection = self.prevArray[indexPath.row]
}
regView.prevSelection = selection
regView.prevSelectionType = selectionPrev
}
}
func updateSearchResultsForSearchController(searchController: UISearchController)
{
if searchController.searchBar.text != ""{
filteredTableData.removeAll(keepCapacity: true)
let searchPredicate = NSPredicate(format: "SELF CONTAINS[c] %#", searchController.searchBar.text!)
if self.selectionPrev != "ed" {
let array = (self.prevArray as NSArray).filteredArrayUsingPredicate(searchPredicate)
filteredTableData = array as! [String]
// edAlert = 0
} else {
let array = (self.prevArray as NSArray).filteredArrayUsingPredicate(searchPredicate)
filteredTableData = array as! [String]
// edAlert = 1
}
self.tableView.reloadData()
} else {
self.tableView.reloadData()
}
}
}

Answer 1

To check version you can do this:
switch UIDevice.currentDevice().systemVersion.compare("8.0.0", options: NSStringCompareOptions.NumericSearch) {
case .OrderedSame, .OrderedDescending:
println("iOS >= 8.0")
case .OrderedAscending:
println("iOS < 8.0")
}
But most likely you just need to check if the class is available and then instantiate it:
if NSClassFromString("UISearchController") != nil {
// init and use ...
}
This is called "weakly linked" class.
EDIT:
Also you can use preprocessor to include/exclude any code before compilation, i.e.:
#if __IPHONE_8_0
class RegData2: UITableViewController, UISearchResultsUpdating {
#else
class RegData2: UITableViewController {
#endif
More info here and here and also here.