swift中类的属性列表 [英] List of class's properties in swift

问题描述

注意:在此处为目标 c 发布了一个类似的问题，但我想快速实现.

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

我有一个像这样在 swift 中声明的类:

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)
    }
}

现在我想在 swift enlisting 中获取一个数组:dateDisplayLabel、nameDisplayLabel.

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

我怎样才能做到这一点?

How can I achieve this?

推荐答案

Using Mirror

这是一个有一些限制的纯 Swift 解决方案:

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"]

限制:

• 为 Objective-C 对象返回一个空数组

• 不会返回计算属性，即:

• Returns an empty array for Objective-C objects

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

var favoriteFood: String { return "Lemon Cake" }

如果 self 是一个类的实例(相对于一个结构体)，它不会报告它的超类的属性，即:

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"

您可以使用 superclassMirror() 解决此问题，具体取决于您想要的行为.

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

如果您使用的是 Objective-C 对象，您可以使用这种方法:

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)

如果classToInspect 是NSURL，则输出到控制台:

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"]

这在操场上是行不通的.只需将 NSURL 替换为 EachDayCell(或重用与扩展相同的逻辑)，它应该可以工作.

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

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