似乎 Swift 4
正在实现不同的方法来(void)setValuesForKeysWithDictionary()，在 Swift 4 中，这个函数的合适替代品是什么？
我有结构
struct User {
let name: String?
let email: String?
}
dictionaryOfUsers来自数据结构，其值根据数据库中的用户数量动态呈现：
let dictionaryOfUsers = [{key1: "name1", key2 : "name1@xyz.com"}, {key1 : "name2", key2 : "name2@gmail.com"} ]
let users = [User]
现在我想使用这个函数来创建我的用户数组，以便在 Swift 4 中创建字典：
for dictionary in dictionaryOfUsers {
let user = User()
user.setValuesForKeysWithDictionary(dictionary)
并附加到用户
users.append(user)
}
请尝试以下方法：
func setValuesForKeys(_ keyedValues: [String : Any])
使用给定字典中的值设置接收器的属性，使用其键标识属性。默认实现为每个键值对调用
setValue(_:forKey:)...
您的代码有许多小问题 - 也有一些主要问题（有关更多信息，请参阅 matt 答案）。无论如何，我认为这应该完成您所追求的：
import Foundation
class User: NSObject {
@objc var name: String!
@objc var email: String!
}
let dictionaryOfUsers = [
["name": "name1", "email": "name1@xyz.com"],
["name": "name2", "email": "name2@gmail.com"]
]
var users = [User]()
for dictionary in dictionaryOfUsers {
let user = User()
user.setValuesForKeys(dictionary)
users.append(user)
}
问题是你试图在结构上使用Cocoa键值编码——这就是setValuesForKeys(_:)的来源。你不能这么做。可可是Objective-C;Objective-C不知道Cocoa结构是什么。您需要User是从 NSObject 派生的@objc类，并且它的所有属性也需要作为@objc公开。
或者，使用新的 Swift 4 键路径功能，该功能可以通过其键访问结构属性。例：
struct User {
var name: String?
var email: String?
}
let arrayOfDicts = [
[User.name: "name1", User.email : "name1@xyz.com"],
[User.name : "name2", User.email : "name2@gmail.com"]
]
for d in arrayOfDicts {
var user = User()
for key in d.keys {
user[keyPath:key] = d[key]!
}
print(user)
}
/*
User(name: Optional("name1"), email: Optional("name1@xyz.com"))
User(name: Optional("name2"), email: Optional("name2@gmail.com"))
*/
不用
说 Swift 4 没有 setValuesForKeysWithDictionary 方法。此外，当前的 setValuesForKeys 方法在最新的 Xcode 版本的 Swift 4 中经常失败。
我的用户对象如下。
import UIKit
class User: NSObject {
var name: String?
var email: String?
}
我自己对这个问题的解决方案是添加手动键作为 NSDictionary，如下所示。
let user = User()
user.email = (snapshot.value as? NSDictionary)?["email"] as? String ?? ""
user.name = (snapshot.value as? NSDictionary)?["name"] as? String ?? ""
print(user.email as Any)
print(user.name as Any)
它没有任何故障。试试吧。
我正在做一些事情。万一有帮助...P.S：请使用泛型进行优化。
import Foundation
import CoreData
enum ModelInitializationResult {
case none
case completedWithoutErrors
case completedWithNullDataErrors
case completedWithNoSuchKeyErrors
}
extension NSManagedObject {
//Note: For this to work, the keys in the dictionary should be same as attibute name of this class
func initializeModelFromDictionary(dictionary: [String:Any] ) -> ModelInitializationResult{
var completionResult = ModelInitializationResult.none
let modelAttributes = self.entity.attributesByName
let modelAttributeKeys = modelAttributes.keys
for case let (keyToSet, valueToSet) in dictionary {
//check for invalid key
guard modelAttributeKeys.contains(keyToSet) else{
completionResult = .completedWithNoSuchKeyErrors
continue;
}
//check valueToSetType for Null
let valueToSetType = type(of: valueToSet)
guard valueToSetType != NSNull.self else{
print("ERROR: Found NSNUll for value to set")
completionResult = .completedWithNullDataErrors
continue;
}
//Check desiredType ; set value for defined types
let modelAttributeValue = modelAttributes[keyToSet]
let modelAttributeType = modelAttributeValue?.attributeType
switch (modelAttributeType!) {
case .undefinedAttributeType :
print("Error : undefinedAttributeType")
case .integer16AttributeType, .integer32AttributeType, .integer64AttributeType :
if let anInt = valueToSet as? Int{
self.setValue(anInt, forKey: keyToSet)
}
else{
//print(Pretty//printedFunction(),"Error in setting value for key:(keyToSet) Incompatible type")
}
case .stringAttributeType :
if let anString = valueToSet as? String{
self.setValue(anString, forKey: keyToSet)
}
else{
//print(Pretty//printedFunction(),"Error in setting value for key:(keyToSet) Incompatible type")
}
case .booleanAttributeType :
if let aBool = valueToSet as? Bool{
self.setValue(aBool, forKey: keyToSet)
}
else{
//print(Pretty//printedFunction(),"Error in setting value for key:(keyToSet) Incompatible type")
}
case .dateAttributeType :
if let aDate = valueToSet as? Date{
self.setValue(aDate, forKey: keyToSet)
}
else{
//print(Pretty//printedFunction(),"Error in setting value for key:(keyToSet) Incompatible type")
}
case .binaryDataAttributeType :
if let aData = valueToSet as? Data{
self.setValue(aData, forKey: keyToSet)
}
else{
//print(Pretty//printedFunction(),"Error in setting value for key:(keyToSet) Incompatible type")
}
case .transformableAttributeType :// If your attribute is of NSTransformableAttributeType,
//print(Pretty//printedFunction(), "desiredType : transformableAttributeType")
if let anObject = valueToSet as? NSObject {
self.setValue(anObject, forKey: keyToSet)
}
else{
//print(Pretty//printedFunction(),"Error in setting value for key:(keyToSet) Incompatible type")
}
case .doubleAttributeType :
//print(Pretty//printedFunction(), "desiredType : doubleAttributeType")
if let anObject = valueToSet as? Double {
self.setValue(anObject, forKey: keyToSet)
}
else{
//print(Pretty//printedFunction(),"Error in setting value for key:(keyToSet) Incompatible type")
}
case .floatAttributeType :
//print(Pretty//printedFunction(), "desiredType : floatAttributeType")
if let anObject = valueToSet as? Float {
self.setValue(anObject, forKey: keyToSet)
}
else{
//print(Pretty//printedFunction(),"Error in setting value for key:(keyToSet) Incompatible type")
}
case .decimalAttributeType :
print("Error: Data type decimalAttributeType Not handled(String(describing: modelAttributeType))")
case .objectIDAttributeType:
print("Error: Data type transformableAttributeType Not handled(String(describing: modelAttributeType))")
default :
print("ERROR : (String(describing: modelAttributeType))")
}
}
return completionResult
}
func toDictionary() -> [String:Any] {
let keys = Array(self.entity.attributesByName.keys)
let dict = self.dictionaryWithValues(forKeys: keys)
return dict
}
func printAllValues (){
for key in self.entity.attributesByName.keys{
let value: Any? = self.value(forKey: key)
print("(key) = (String(describing: value))")
}
}
}