ios Swift 从 NSDictionary 读取数据
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时间：2020-08-31 08:06:39 来源:igfitidea点击:
Swift read data from NSDictionary
提问by MTA
I am using this code to read data from NSDictionary:
我正在使用此代码从NSDictionary以下位置读取数据：
let itemsArray: NSArray = response.objectForKey("items") as! NSArray;
let nextPageToken: String = response.objectForKey("nextPageToken") as! String
var videoIdArray: [String] = []
for (item) in itemsArray {
let videoId: String? = item.valueForKey("id")!.valueForKey("videoId") as? String
videoIdArray.append(videoId!)
}
But when i itemsor nextPageTokenare not exist i get this error:
但是当我items或nextPageToken不存在时，我会收到此错误：
fatal error: unexpectedly found nil while unwrapping an Optional value
Any idea why? how i can fix it?
知道为什么吗？我该如何解决？
回答by Midhun MP
There are two issues in your code:
您的代码中有两个问题：
- You are trying to force unwrap an optional that can be nil. Never use forced unwrapping, if you are not sure whether the data will be available or not.
- You are using
valueForKey:instead ofobjectForKey:for retrieving data from a dictionary. Use objectForKey: instead of valueForKey:for getting data from a dictionary.
- 您正在尝试强制解开一个可以为零的可选项。如果您不确定数据是否可用，切勿使用强制解包。
- 您正在使用
valueForKey:而不是objectForKey:从字典中检索数据。使用objectForKey: 而不是 valueForKey:从字典中获取数据。
You can fix the crash by:
您可以通过以下方式修复崩溃：
let itemsArray: NSArray? = response.objectForKey("items") as? NSArray;
let nextPageToken: String? = response.objectForKey("nextPageToken") as? String
var videoIdArray: [String] = []
if let itemsArray = itemsArray
{
for (item) in itemsArray
{
let videoId: String? = item.objectForKey("id")?.objectForKey("videoId") as? String
if (videoId != nil)
{
videoIdArray.append(videoId!)
}
}
}
