Question

尝试使用follownig获取UIView或UIViewController的所有属性：

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

这适用于UIVIewController，但是UIView似乎没有返回属性，有什么建议吗？

Answer 1

不确定您要实现的目标，但UIView继承了NSObject。因此，您可以使用大量的objc运行时。作为替代方案，您可以执行以下操作：

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"

此外，我确实看到一些将您的代码应用于UIKit对象的奇怪之处。不确定导致失败的变量是什么。它似乎在用Swift编写的NSObject类型上工作正常：

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"

所以要么这是一个bug，要么在Swift＆lt; - ＆gt;中有一些限制。 ObjC在当前版本的Swift中。也许这与@ user3441734在答案中指出的内容有关。

BTW，所有代码都是在操场上最新版本的Xcode（即7.1.1）上运行。

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

你是对的！只需填写错误报告......

或者是破坏，因为我发现了这个

extension UIView : _Reflectable {
}

Swift Mirror反射不返回UIVIew上的属性

2 个答案: