ios - 在 Swift 中从 JSON 对象解析多个数组
<p><p>我正在使用 <code>Swift3</code> 构建一个 <code>iOS 应用程序</code>,对于应用程序的一部分,我向返回的网页发送 <code>HTTP POST</code> 请求一个包含 5 个不同数组的 <code>JSON</code> 对象。我希望在 Swift 中接收此 <code>JSON 对象</code> 并将这些数组以可读格式 (NSArray)。以下正是我的网页返回的内容。</p>
<pre><code>{"className":["U.S. History 2 (AP)","Chemistry (HN)","Algebra 2 (HN)","Spanish 3 (HN)"],"teacherLastName":["Schartner","Racz","Johnson","Burdette"],"teacherFirstName":["Lindsey","Gregory","Shane","Joy"],"teacherTitle":["Mrs.","Mr.","Mr.","Sra."],"classID":["0001","0002","0003","0004"]}
</code></pre>
<p>我正在尝试在我的 Swift 代码中执行以下操作。我不完全确定从这里去哪里,但这就是我目前所拥有的。</p>
<pre><code>func getClassList() -> NSArray{
let myUrl = URL(string: "http://papili.us/studycentral/api/getClassList.php");
var request = URLRequest(url:myUrl!)
request.httpMethod = "POST"// Compose a query string
let postString = "";
request.httpBody = postString.data(using: String.Encoding.utf8);
let task = URLSession.shared.dataTask(with: request) { (data: Data?, response: URLResponse?, error: Error?) in
if error != nil {
print("error=\(error)")
return
}
// Print out response object
print("response = \(response)")
//Convert response sent from a server side script to a NSDictionary object:
do {
let json = try JSONSerialization.jsonObject(with: data!, options: .mutableContainers) as? NSDictionary
if let parseJSON = json {
// Access value of username, name, and email by its key
let newdata : NSDictionary = try JSONSerialization.jsonObject(with: data!, options: JSONSerialization.ReadingOptions.mutableContainers) as! NSDictionary
let info : NSArray =newdata.value(forKey: "className") as! NSArray
self.classList = info
}
} catch {
print(error)
}
}
task.resume()
return self.classList
}
</code></pre>
<p>有人可以解释我需要做什么才能正确读取我的 JSON 对象中的数组吗?非常感谢</p></p>
<br><hr><h1><strong>Best Answer-推荐答案</ strong></h1><br>
<p><p>凯尔,</p>
<p>这里发生了很多事情。您犯的最大错误是将异步函数视为同步函数。您传递给 <code>dataTask</code> 的闭包会异步执行,这意味着在您 <code>return self.classList</code> 时它还没有完成(很可能)。为了解决这个问题,你的 <code>getClassList</code> 方法本身应该有一个闭包,它会在数据任务完成时调用它。</p>
<p>看起来像这样:</p>
<pre><code>func getClassList(completion: ((NSArray?, NSError?) -> Void)?) {
let myUrl = URL(string: "http://papili.us/studycentral/api/getClassList.php");
var request = URLRequest(url:myUrl!)
request.httpMethod = "POST"// Compose a query string
let postString = "";
request.httpBody = postString.data(using: String.Encoding.utf8);
let task = URLSession.shared.dataTask(with: request) { (data: Data?, response: URLResponse?, error: Error?) in
if error != nil {
print("error=\(error)")
completion?(nil, error)
return
}
// Print out response object
print("response = \(response)")
//Convert response sent from a server side script to a NSDictionary object:
do {
let json = try JSONSerialization.jsonObject(with: data!, options: .mutableContainers) as? NSDictionary
if let parseJSON = json {
// Access value of username, name, and email by its key
let newdata : NSDictionary = try JSONSerialization.jsonObject(with: data!, options: JSONSerialization.ReadingOptions.mutableContainers) as! NSDictionary
let info : NSArray =newdata.value(forKey: "className") as! NSArray
completion?(info, nil)
}
} catch {
print(error)
completion?(nil, error)
}
}
task.resume()
}
</code></pre>
<p>您访问这些数据的方法是调用 <code>getClassList</code> 并使用一个带有 <code>NSArray?</code> 和 <code>NSError?</code> 的闭包并执行您的操作想和他们在一起。这类似于您调用 <code>dataTask</code> 的方式。</p>
<p>此外,在我看来,这个请求更像是 <code>GET</code> 而不是 <code>POST</code>。仔细检查您是否根据您使用的 API 构建请求。</p>
<p>我建议清理此代码还有许多其他方法,但我认为这些是插入您前进的要点。</p></p>
<p style="font-size: 20px;">关于ios - 在 Swift 中从 JSON 对象解析多个数组,我们在Stack Overflow上找到一个类似的问题:
<a href="https://stackoverflow.com/questions/42179382/" rel="noreferrer noopener nofollow" style="color: red;">
https://stackoverflow.com/questions/42179382/
</a>
</p>
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