我正在使用以下 Class 从外部数据库接收数据:
import Foundation
protocol HomeModelProtocal: class {
func itemsDownloaded(items: NSArray)
}
class HomeModel: NSObject, NSURLSessionDataDelegate {
//properties
weak var delegate: HomeModelProtocal!
var data : NSMutableData = NSMutableData()
var mi_movil: String = ""
let misDatos:NSUserDefaults = NSUserDefaults.standardUserDefaults()
var urlPath: String = "http:...hidden here.."
let parametros = "?id="
func downloadItems() {
mi_movil = misDatos.stringForKey("ID_IPHONE")!
print ("mi_movil en HOMEMODEL:",mi_movil)
urlPath = urlPath + parametros + mi_movil
let url: NSURL = NSURL(string: urlPath)!
var session: NSURLSession!
let configuration = NSURLSessionConfiguration.defaultSessionConfiguration()
print ("LA URL ES: ",url)
session = NSURLSession(configuration: configuration, delegate: self, delegateQueue: nil)
let task = session.dataTaskWithURL(url)
task.resume()
}
func URLSession(session: NSURLSession, dataTask: NSURLSessionDataTask, didReceiveData data: NSData) {
self.data.appendData(data);
}
func URLSession(session: NSURLSession, task: NSURLSessionTask, didCompleteWithError error: NSError?) {
if error != nil {
print("Failed to download data")
}else {
print("Data downloaded")
self.parseJSON()
}
}
func parseJSON() {
var jsonResult: NSMutableArray = NSMutableArray()
do{
jsonResult = try NSJSONSerialization.JSONObjectWithData(self.data, options:NSJSONReadingOptions.AllowFragments) as! NSMutableArray
} catch let error as NSError {
print(error)
}
var jsonElement: NSDictionary = NSDictionary()
let locations: NSMutableArray = NSMutableArray()
for(var i = 0; i < jsonResult.count; i++)
{
jsonElement = jsonResult[i] as! NSDictionary
print (jsonElement)
let location = MiAutoModel()
//the following insures none of the JsonElement values are nil through optional binding
if let id_mis_autos = jsonElement["id_mis_autos"] as? String,
let modelo = jsonElement["modelo"] as? String,
let ano = jsonElement["ano"] as? String,
let id_movil = jsonElement["id_movil"] as? String
{
location.id_mis_autos = id_mis_autos
location.modelo = modelo
location.ano = ano
location.id_movil = id_movil
}
locations.addObject(location)
}
dispatch_async(dispatch_get_main_queue(), { () -> Void in
self.delegate.itemsDownloaded(locations)
})
}
}
如果有接收到的数据，它工作正常但如果没有数据则抛出异常:
Could not cast value of type '__NSArray0' (0x1a0dd2978) to 'NSMutableArray' (0x1a0dd3490)
如果没有数据，我应该更改什么来检测以避免异常？
最佳答案
由于您似乎没有在任何地方修改 jsonResult，因此显而易见的选择是将其设为 NSArray 而不是 NSMutableArray，并更改向下转换以匹配它。
关于ios - 如果没有收到数据则抛出异常，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/37602056/