Question

我在数组中有自定义对象（Scan）。我想删除一个特定的对象，它不起作用。这是我的代码：

class Scan : NSObject, NSCoding {

    let code : String
    let title : String
    let scanDate : NSDate

    init(code: String, title: String, scanDate: NSDate) {
        self.code = code
        self.title = title
        self.scanDate = scanDate
    }

    // MARK: NSCoding

    required convenience init?(coder decoder: NSCoder) {
        guard let code = decoder.decodeObjectForKey("code") as? String,
            let title = decoder.decodeObjectForKey("title") as? String,
            let scanDate = decoder.decodeObjectForKey("scanDate") as? NSDate
            else { return nil }

        self.init(code: code, title: title, scanDate: scanDate)
    }

    func encodeWithCoder(coder: NSCoder) {
        coder.encodeObject(self.title, forKey: "title")
        coder.encodeObject(self.code, forKey: "code")
        coder.encodeObject(self.scanDate, forKey: "scanDate")
    }
}

func == (lhs: Scan, rhs: Scan) -> Bool {
    return lhs.code == rhs.code
}

在另一堂课中：

func saveScan(scan: Scan){
        var allScans = scans()
        allScans.append(scan)
        NSKeyedArchiver.archiveRootObject(allScans, toFile: filePath)

    }

    func deleteScan(scan: Scan) {
        var archivedScans = scans()
        archivedScans.removeObject(scan)
        NSKeyedArchiver.archiveRootObject(archivedScans, toFile: filePath)
    }

    func scans() -> [Scan] {
        let scans =  NSKeyedUnarchiver.unarchiveObjectWithFile(filePath) as? [Scan] ?? [Scan]()
        return scans
    }

数组扩展名：

extension Array where Element : Equatable {

    mutating func removeObject(object : Generator.Element) {
        if let index = self.indexOf(object) {
            self.removeAtIndex(index)
        }
    }
}

archivedScans.removeObject(scan)无法正常工作（archivedScans在removeObject之前和之后具有相同的元素）。你知道为什么删除不起作用吗？

Answer 1

由于Scan类是NSObject的子类，因此未正确实现相等性。我们应该覆盖isEqual和hash方法

正确的代码：

import Foundation

class Scan : NSObject, NSCoding {

    let code : String
    let title : String
    let scanDate : NSDate

    init(code: String, title: String, scanDate: NSDate) {
        self.code = code
        self.title = title
        self.scanDate = scanDate
    }

    // MARK: NSCoding

    required convenience init?(coder decoder: NSCoder) {
        guard let code = decoder.decodeObjectForKey("code") as? String,
            let title = decoder.decodeObjectForKey("title") as? String,
            let scanDate = decoder.decodeObjectForKey("scanDate") as? NSDate
            else { return nil }

        self.init(code: code, title: title, scanDate: scanDate)
    }

    func encodeWithCoder(coder: NSCoder) {
        coder.encodeObject(self.title, forKey: "title")
        coder.encodeObject(self.code, forKey: "code")
        coder.encodeObject(self.scanDate, forKey: "scanDate")
    }

    override func isEqual(object: AnyObject?) -> Bool {
        if let object = object as? Scan {
            return self.code == object.code
        }
        return false
    }

    override var hash: Int {
        return self.code.hashValue
    }
}

删除数组中的自定义对象

1 个答案: