我有以下课程
class BannerResponse : NSObject{
let URL = "Url";
let CONTACT_NO = "ContactNo";
let IMAGE = "Image";
let BIG_IMAGE = "BigImage";
let ID = "Id";
let TITLE = "Title";
let NO_VIEW = "NoView";
let START_DATE = "StartDate";
let END_DATE = "EndDate";
var url:String;
var contactNo:String;
var image:String;
var bigImage:String;
var title:String;
var id:Int;
var noView:Int;
var startDate:String;
var endDate:String;
init(data : NSDictionary){
url = data[URL] as! String;
contactNo = data[CONTACT_NO] as! String;
image = data[IMAGE] as! String;
bigImage = data[BIG_IMAGE] as! String;
title = data[TITLE] as! String;
id = data[ID] as! Int;
noView = data[NO_VIEW] as! Int;
startDate = data[START_DATE] as! String;
endDate = data[END_DATE] as! String;
}
}
当我运行代码时,我得到以下错误
Could not cast value of type 'NSNull' (0x10a85f378) to 'Nsstring' (0x109eccb20).
编辑
do {
if let json = try NSJSONSerialization.JSONObjectWithData(data!,options: NSJSONReadingOptions.MutableContainers) as? NSDictionary{
onSuccess(BannerResponse(data: json))
}
} catch {
onFail()
}
解决方法
你的一个数据[SOME_KEY]的类型是NSNull而不是String,因为你正在使用强制转换为String！该应用程序崩溃.
你可以做以下两件事之一：
>将BannerResponse类的变量更改为可选.用吗？代替 ！在init方法中设置值时.像这样：
`
var title: String?
init(data: NSDictionary)
{
self.title = data[TITLE] as? String
}
要么
>使用？代替 ！在init方法中设置值但在dict [SOME_KEY]为nil或不是预期类型时设置默认值.这看起来像这样：
`
if let title = data[TITLE] as? String
{
self.title = title
}
else
{
self.title = "default title"
}
// Shorthand would be:
// self.title = data[TITLE] as? String ?? "default title"
我想第三件事是确保服务器永远不会发送空值.但这是不切实际的,因为从来没有这样的事情.您应该编写客户端代码,以假设JSON中的每个值都可以为null或意外类型.