我正在尝试在for in循环中为数组quandlURLs运行以下函数。我在“ loadDataFromURL”行中遇到一条错误，说：无法将类型为[String]的值转换为类型为'Sting'的预期参数。有人可以告诉我我在这里想念的东西吗？谢谢！！
class func getDataFromQuandlWithSuccess(success: ((Quandl: NSData!) -> Void)) {
let quandlGold = "https://www.quandl.com/api/v3/datasets/LBMA/GOLD.json?auth_token=xyzDP7Cj-2F_Jss7sYHf&rows=1"
quandlURLs = [quandlGold, quandlSilver,quandlPlatinum,quandlPalladium]
var index: Int
var urlData = [String]()
for index in quandlURLs {
loadDataFromURL(NSURL(string: quandlURLs[index])!, completion:{(data, error) -> Void in
//2
if let urlData[index] = data {
//3
success(Quandl: urlData[index])
//below worked and showed raw data
//print("Successful \(urlData)")
}
})
}
}
这是loadDataFromURL函数
class func loadDataFromURL(url: NSURL, completion:(data: NSData?, error: NSError?) -> Void) {
let session = NSURLSession.sharedSession()
// Use NSURLSession to get data from an NSURL
let loadDataTask = session.dataTaskWithURL(url, completionHandler: { (data: NSData?, response: NSURLResponse?, error: NSError?) -> Void in
if let responseError = error {
completion(data: nil, error: responseError)
} else if let httpResponse = response as? NSHTTPURLResponse {
if httpResponse.statusCode != 200 {
let statusError = NSError(domain:"com.raywenderlich", code:httpResponse.statusCode, userInfo:[NSLocalizedDescriptionKey : "HTTP status code has unexpected value."])
completion(data: nil, error: statusError)
} else {
completion(data: data, error: nil)
}
}
})
loadDataTask.resume()
}
}
您要做的就是更改for index in quandlURLs为for index in 0..<quandlURLs.count
还有一个问题if let urlData[index] = data，因为您不能对数组使用可选绑定，因此需要定义一个新值，所以go if let urlDataEntry = data，在这种情况下，urlIndex数组应为NSData类型。
您也不需要var index: Int线。在创建Int数组的.. <函数上使用for in循环时，会推断Int，并且index变量可在整个for循环中使用。
例如：
class func getDataFromQuandlWithSuccess(success: ((Quandl: NSData!) -> Void)) {
let quandlGold = "https://www.quandl.com/api/v3/datasets/LBMA/GOLD.json?auth_token=xyzDP7Cj-2F_Jss7sYHf&rows=1"
quandlURLs = [quandlGold, quandlSilver,quandlPlatinum,quandlPalladium]
var urlData = [NSData]()
for index in 0..<quandlURLs.count {
loadDataFromURL(NSURL(string: quandlURLs[index])!, completion:{(data, error) -> Void in
//2
if let urlDataEntry = data {
//3
urlData[index] = urlDataEntry
success(Quandl: urlDataEntry)
//below worked and showed raw data
//print("Successful \(urlData)")
}
})
}
}
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