Swift Mirror does not return UIVIew property

Question

Trying to get all properties of a UIView or UIViewController using follownig:

func propertysNames()->[String]{ var s = [String]() for c in Mirror(reflecting: self).children { if let name = c.label{ s.append(name) } } return s } 

This works on the UIVIewController, but the UIView does not seem to return properties, any tips?

Answer 1

Not sure what you are trying to achieve, but UIView inherits NSObject. Because of this, most of the objc runtime is at your disposal. Alternatively, you can do the following:

 import UIKit extension NSObject { func propertysNames() -> [String]{ var count : UInt32 = 0 let classToInspect = self.dynamicType 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] let propertyName = NSString(UTF8String: property_getName(property))! propertyNames.append(propertyName as String) } free(properties) return propertyNames } } print(UIView().propertysNames()) // prints: "["_mayRemainFocused", "_sensitivitySize", "skipsSubviewEnumeration", "viewTraversalMark", "viewDelegate", "monitorsSubtree", "backgroundColorSystemColorName", "currentScreenScale", "maskView", "_userInterfaceIdiom", "hash", "superclass", "description", "debugDescription", "gesturesEnabled", "deliversTouchesForGesturesToSuperview", "deliversButtonsForGesturesToSuperview", "_shouldReverseLayoutDirection", "leadingAnchor", "trailingAnchor", "leftAnchor", "rightAnchor", "topAnchor", "bottomAnchor", "widthAnchor", "heightAnchor", "centerXAnchor", "centerYAnchor", "firstBaselineAnchor", "lastBaselineAnchor", "_keyboardOrientation", "_touchForceObservable", "_inheritedRenderConfig", "_lightStyleRenderConfig", "_accessoryViewFrame", "unsatisfiableConstraintsLoggingSuspended", "hash", "superclass", "description", "debugDescription", "hash", "superclass", "description", "debugDescription", "userInteractionEnabled", "tag", "layer", "focused", "semanticContentAttribute", "interactionTintColor", "_layoutDebuggingIdentifier", "_countOfMotionEffectsInSubtree", "_maskView", "_ancestorDefinesTintColor", "_ancestorDefinesTintAdjustmentMode", "_presentationControllerToNotifyOnLayoutSubviews", "_rawLayoutMargins", "_inferredLayoutMargins", "_dontUpdateInferredLayoutMargins", "_tracksFocusedAncestors", "_countOfFocusedAncestorTrackingViewsInSubtree", "_mutableLayoutGuides", "_mutableLayoutArrangements", "_hiddenManagedByLayoutArrangementCount", "_pendingHiddenCount", "previewingSegueTemplateStorage", "_continuousCornerRadius", "_canBeParentTraitEnviroment", "_layoutEngine", "_boundsWidthVariable", "_boundsHeightVariable", "_minXVariable", "_minYVariable", "_internalConstraints", "_constraintsExceptingSubviewAutoresizingConstraints", "unsatisfiableConstraintsLoggingSuspended", "_shouldArchiveUIAppearanceTags", "_interactionTintColor", "_backdropMaskViewForGrayscaleTint", "_backdropMaskViewForColorTint", "_backdropMaskViewForFilters", "_backdropMaskViews", "_wantsGeometryChangeNotification", "contentSizeNotificationToken", "layoutMarginsGuide", "readableContentGuide", "hash", "superclass", "description", "debugDescription", "traitCollection", "preferredFocusedView", "center", "bounds", "transform", "collisionBoundsType", "collisionBoundingPath"]\n" 

In addition, I see some oddities when applying your code to UIKit objects. Not sure which variable is causing the error. It seems to work great on NSObject types written in Swift:

 import UIKit class Fruit { var type=1 var name="Apple" var delicious=true } var s = [String]() for c in Mirror(reflecting: Fruit()).children { if let name = c.label{ s.append(name) } } print(s) // works: "["type", "name", "delicious"]\n" class FruitNSObject: NSObject { var type:NSNumber=1 var name:NSString="Apple" var delicious=true } s = [String]() for c in Mirror(reflecting: FruitNSObject()).children { if let name = c.label { s.append(name) } } print(s) // works: "["type", "name", "delicious"]\n" s = [String]() for c in Mirror(reflecting: UIView()).children { if let name = c.label { s.append(name) } } print(s) // doesn't work: "[]\n" s = [String]() for c in Mirror(reflecting: UIViewController()).children { if let name = c.label { s.append(name) } } print(s) // doesn't work: "[]\n" 

Thus, this is either a mistake or a limitation in Swift ↔ ObjC in the current version of Swift. Perhaps this is due to what @ user3441734 indicated in his answer.

BTW, all the code was launched in the latest version of Xcode (this is 7.1.1) on the playground.

Answer 2

 import UIKit let viewController = UIViewController() let view = UIView() class MyViewController: UIViewController { let i = 1 let myView = MyView() } class MyView : UIView { let label = UILabel() let i = 1 } Mirror(reflecting: MyViewController()).children.count // 2 Mirror(reflecting: MyView()).children.count // 0 

You're right! Just fill out the bug report ...

or is it sabotage because I found it

 extension UIView : _Reflectable { }