List of class's properties in swift

Question

Note: there is a similar question posted for objective c over here, but I want to achieve it in swift.

I have a class declared in swift like this:

import UIKit  class EachDayCell : UITableViewCell {      @IBOutlet var dateDisplayLabel : UITextField     @IBOutlet var nameDisplayLabel : UITextField      @IBAction func goToPendingItems(sender : AnyObject) {     }     @IBAction func showDateSelectionPicker(sender : AnyObject) {     }      init(style: UITableViewCellStyle, reuseIdentifier: String!)     {         super.init(style: style, reuseIdentifier: reuseIdentifier)     } } 

Now I want to get an array in swift enlisting: dateDisplayLabel, nameDisplayLabel.

How can I achieve this?

Answer 1

Using Mirror

Here's a pure Swift solution with some limitations:

protocol PropertyNames {     func propertyNames() -> [String] }  extension PropertyNames {     func propertyNames() -> [String] {         return Mirror(reflecting: self).children.flatMap { $0.label }     } }  class Person : PropertyNames {     var name = "Sansa Stark"     var awesome = true }  Person().propertyNames() // ["name", "awesome"] 

Limitations:

• Returns an empty array for Objective-C objects

• Will not return computed properties, i.e.:

  var favoriteFood: String { return "Lemon Cake" } 

• If self is an instance of a class (vs., say, a struct), this doesn't report its superclass's properties, i.e.:

  class Person : PropertyNames {     var name = "Bruce Wayne" }  class Superhero : Person {     var hasSuperpowers = true }  Superhero().propertyNames() // ["hasSuperpowers"] — no "name" 

  You could work around this using superclassMirror() depending on your desired behavior.

Using class_copyPropertyList

If you're using Objective-C objects you can use this approach:

var count = UInt32() let classToInspect = NSURL.self let properties : UnsafeMutablePointer <objc_property_t> = class_copyPropertyList(classToInspect, &count) var propertyNames = [String]() let intCount = Int(count) for var i = 0; i < intCount; i++ {     let property : objc_property_t = properties[i]     guard let propertyName = NSString(UTF8String: property_getName(property)) as? String else {         debugPrint("Couldn't unwrap property name for \(property)")         break     }      propertyNames.append(propertyName) }  free(properties) print(propertyNames) 

The output to the console if classToInspect is NSURL:

["pathComponents", "lastPathComponent", "pathExtension", "URLByDeletingLastPathComponent", "URLByDeletingPathExtension", "URLByStandardizingPath", "URLByResolvingSymlinksInPath", "dataRepresentation", "absoluteString", "relativeString", "baseURL", "absoluteURL", "scheme", "resourceSpecifier", "host", "port", "user", "password", "path", "fragment", "parameterString", "query", "relativePath", "hasDirectoryPath", "fileSystemRepresentation", "fileURL", "standardizedURL", "filePathURL"]

This won't work in a playground. Just replace NSURL with EachDayCell (or reuse the same logic as an extension) and it should work.

Answer 2

Here is another version.I think this is much simple and pure.

Swift 2.0

protocol Reflectable {   func properties()->[String] }  extension Reflectable {     func properties()->[String]{         var s = [String]()         for c in Mirror(reflecting: self).children         {             if let name = c.label{                 s.append(name)             }         }         return s     } }   class Test:Reflectable {     var name99:String = ""     var name3:String = ""     var name2:String = "" }  Test().properties() 

Swift 1.2

class Reflect:NSObject {     func properties()->[String]     {         let m = reflect(self)         var s = [String]()         for i in 0..<m.count         {             let (name,_)  = m[i]             if name == "super"{continue}             s.append(name)         }         return s     } }  class Test:Reflect {     var name99:String = ""     var name3:String = ""     var name2:String = "" }  Test().properties()