JSON解析swift,数组在NSURLSession之外没有任何值 [英] JSON parsing swift, array has no value outside NSURLSession
问题描述
我试图在swift中调用json webservice,使用以下代码并在swift IOS中的 tableview
中显示它。
I am trying to call a json webservice in swift, With the following code and display it in tableview
in swift IOS.
/*declared as global*/ var IdDEc = [String]() // string array declared globally
//inside viewdidload
let url = NSURL(string: "http://192.1.2.3/PhpProject1/getFullJson.php")
let task = NSURLSession.sharedSession().dataTaskWithURL(url!) {(data, response, error) in
let json1 = NSString(data: data!, encoding: NSUTF8StringEncoding)
print("json string is = ",json1) // i am getting response here
let data = json1!.dataUsingEncoding(NSUTF8StringEncoding, allowLossyConversion: false)
do {
let json = try NSJSONSerialization.JSONObjectWithData(data!, options: .MutableContainers) as! NSArray
for arrayData in json {
let notId = arrayData["ID"] as! String
self.IdDEc.append(notId)
}
print(" id = ",IdDEc) //here i am getting values
} catch let error as NSError {
print("Failed to load: \(error.localizedDescription)")
}
print(" id out count = ",self.IdDEc.count) //here also
}
print(" id out count = ",self.IdDEc.count) // not here
task.resume()
我将数组IdDEc声明为全局,仍然该数组的范围仅驻留在NSURLSession中,
i declared the array IdDEc as global, still the scope of that array resides inside NSURLSession only,
此外,我还想使用此数组来填充tableview。
以下是json输出文件示例
Also i want to use this array to populate tableview. Here is the sample json output file
[
{"ID":"123" , "USER":"philip","AGE":"23"},
{"ID":"344","USER":"taylor","AGE":"29"},
{"ID":"5464","USER":"baker","AGE":"45"},
{"ID":"456","USER":"Catherine","AGE":"34"}
]
我是swift中的新手请帮助
I am a newbee in swift please help
推荐答案
这个想法是使用回调 。
The idea is to use a "callback".
在这里,我为你想要的NSArray做了一个:
Here, I've made one for the NSArray you want to get:
completion: (dataArray: NSArray)->()
我们创建了一个获取数组的函数,我们将此回调添加到函数的签名中:
We create a function to get the array, and we add this callback to the function's signature:
func getDataArray(urlString: String, completion: (dataArray: NSArray)->())
一旦阵列准备好我们就会使用回调:
and as soon as the array is ready we'll use the callback:
completion(dataArray: theNSArray)
以下是完整函数的样子:
Here's how the complete function could look like:
func getDataArray(urlString: String, completion: (dataArray: NSArray)->()) {
if let url = NSURL(string: urlString) {
NSURLSession.sharedSession().dataTaskWithURL(url) {(data, response, error) in
if error == nil {
if let data = data,
json1 = NSString(data: data, encoding: NSUTF8StringEncoding),
data1 = json1.dataUsingEncoding(NSUTF8StringEncoding, allowLossyConversion: false) {
do {
let json = try NSJSONSerialization.JSONObjectWithData(data1, options: [])
if let jsonArray = json as? NSArray {
completion(dataArray: jsonArray)
}
} catch let error as NSError {
print(error.localizedDescription)
}
} else {
print("Error: no data")
}
} else {
print(error!.localizedDescription)
}
}.resume()
}
}
现在我们像这样使用这个函数,不再是异步问题:
Now we use this function like this, no more asynchronous issues:
getDataArray("http://192.1.2.3/PhpProject1/getFullJson.php") { (dataArray) in
for dataDictionary in dataArray {
if let notId = dataDictionary["ID"] as? String {
self.IdDEc.append(notId)
}
}
print("id out count = ", self.IdDEc.count)
}
Swift 3 更新+修正和改进。
func getContent(from url: String, completion: @escaping ([[String: Any]])->()) {
if let url = URL(string: url) {
URLSession.shared.dataTask(with: url) { (data, response, error) in
if error == nil {
if let data = data {
do {
let json = try JSONSerialization.jsonObject(with: data, options: [])
if let content = json as? [[String: Any]] { // array of dictionaries
completion(content)
}
} catch {
// error while decoding JSON
print(error.localizedDescription)
}
} else {
print("Error: no data")
}
} else {
// network-related error
print(error!.localizedDescription)
}
}.resume()
}
}
getContent(from: "http://192.1.2.3/PhpProject1/getFullJson.php") { (result) in
// 'result' is what was given to 'completion', an array of dictionaries
for dataDictionary in result {
if let notId = dataDictionary["ID"] as? String {
// ...
}
}
}
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