blocks|key|124231|text|错误的原因是jsonDict["totalfup"]是一个字符串(NSTaggedPointerString是NSString的子类)，所以您应该将String转换为Double。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|124232|在强制展开之前，请确保捕获异常并检查类型!|BOLD|124233|totalData+=+(jsonDict["totalfup"]+as!+NSString).doubleValue|code-block|syntax|javascript|124234|对于安全，使用if+let|124235|//+check+dict["totalfup"]+is+a+String?
if+let+totalfup+=+(dict["totalfup"]+as?+NSString)?.doubleValue+{
++//+totalfup+is+a+Double+here+
}
else+{
++//+dict["totalfup"]+isn't+a+String
++//+you+can+try+to+'as?+Double'+here
}|124236|entityMap^0|6|K|X|L|1J|8|0|0|L|0|0|2|2|7|6|0|0^^$0|@$1|2|3|4|5|6|7|T|8|@$9|U|A|V|B|C]|$9|W|A|X|B|C]|$9|Y|A|Z|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|10|8|@$9|11|A|12|B|H]]|D|@]|E|$]]|$1|I|3|J|5|K|7|13|8|@]|D|@]|E|$L|M]]|$1|N|3|O|5|6|7|14|8|@$9|15|A|16|B|H]|$9|17|A|18|B|C]]|D|@]|E|$]]|$1|P|3|Q|5|K|7|19|8|@]|D|@]|E|$L|M]]|$1|R|3|-4|5|6|7|1A|8|@]|D|@]|E|$]]]|S|$]]

The reason of the error is <code>jsonDict["totalfup"]</code> is a String (<code>NSTaggedPointerString</code> is a subclass of <code>NSString</code>) , so you should convert String to Double.

Please make sure, catch exception and check type before force-unwrap !

<pre><code>totalData = (jsonDict["totalfup"] as! NSString).doubleValue
</code></pre>

For safety, using <code>if let</code>:

<pre><code>// check dict["totalfup"] is a String?
if let totalfup = (dict["totalfup"] as? NSString)?.doubleValue {
 // totalfup is a Double here 
}
else {
 // dict["totalfup"] isn't a String
 // you can try to 'as? Double' here
}
</code></pre>

blocks|key|127244|text|失败的原因是JSON返回的是String值，而不是数字。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|127245|如果返回的JSON数据只包含这两个键值对，则将类型声明为[String:String]，从而避免类型转换。|127246|在任何情况下，您都必须将更新变量的代码放入do+-+catch表达式的“好”分支。|127247|struct+Usage+{
++++var+totalData+=+0.0
++++var+remainingTotalData+=+0.0

++++init(jsonData:+NSData)+{+//+Swift+3:+Data

++++++++do+{
++++++++++++let+jsonDict+=+try+NSJSONSerialization.JSONObjectWithData(jsonData,+options:+[])+as!+[String:+String]++++++++++++++++
++++++++++++//+Swift+3:+let+jsonDict+=+try+NSJSONSerialization.jsonObject(with:+jsonData)+as!+[String:+String]
++++++++++++totalData+=+Double(jsonDict["totalfup"]!)
++++++++++++remainingTotalData+=+Double(jsonDict["totalrem"]!)
++++++++}+catch+{
++++++++++++print("Error+occurred+parsing+data:+\(error)")
++++++++}
++++}
}|code-block|syntax|javascript|127248|entityMap^0|E|6|0|S|F|0|L|A|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|T|8|@$9|U|A|V|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|W|8|@$9|X|A|Y|B|C]]|D|@]|E|$]]|$1|J|3|K|5|L|7|Z|8|@]|D|@]|E|$M|N]]|$1|O|3|-4|5|6|7|10|8|@]|D|@]|E|$]]]|P|$]]

The failure reason is that the JSON returns <code>String</code> values, not numbers.

If the returned JSON data contains only these two key value pairs declare the type as <code>[String:String]</code> that avoids the type casting.

In any case you have to put the code to update the variables into the "good" branch of the <code>do - catch</code> expression.

<pre><code>struct Usage {
 var totalData = 0.0
 var remainingTotalData = 0.0

 init(jsonData: NSData) { // Swift 3: Data

 do {
 let jsonDict = try NSJSONSerialization.JSONObjectWithData(jsonData, options: []) as! [String: String] 
 // Swift 3: let jsonDict = try NSJSONSerialization.jsonObject(with: jsonData) as! [String: String]
 totalData = Double(jsonDict["totalfup"]!)
 remainingTotalData = Double(jsonDict["totalrem"]!)
 } catch {
 print("Error occurred parsing data: \(error)")
 }
 }
}
</code></pre>

blocks|key|124252|text|我想这对你有帮助|type|unstyled|depth|inlineStyleRanges|entityRanges|data|124253|totalData+=+Double(jsonDict["totalfup"]+as!+String)!|code-block|syntax|javascript|124254|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

I think this could help you

<pre><code>totalData = Double(jsonDict["totalfup"] as! String)!
</code></pre>

blocks|key|127268|text|为什么不直接使用Swift的原生类型呢？|type|unstyled|depth|inlineStyleRanges|entityRanges|data|127269|import+Foundation

struct+Usage+{
++++var+totalData:+Double+=+0
++++var+remainingTotalData:+Double+=+0

++++init(jsonData:+NSData)+{
++++++++do+{
++++++++++++if+let+jsonDict+=+try+NSJSONSerialization.JSONObjectWithData(jsonData,+options:+[])+as?+[String:Double]+{
++++++++++++++++totalData+=+jsonDict["totalfup"]+??+0
++++++++++++++++remainingTotalData+=+jsonDict["totalrem"]+??+0
++++++++++++}
++++++++}+catch+{
++++++++++++print("Error+occurred+parsing+data:+\(error)")
++++++++}
++++}
}

if+let+data+=+"{\"totalfup\":96.340899,\"totalrem\":3548710948}".dataUsingEncoding(NSUTF8StringEncoding)+{
++++let+usage+=+Usage(jsonData:+data)
++++dump(usage)
++++/*
++++▿+Usage
++++++-+totalData:+96.340899
++++++-+remainingTotalData:+3548710948.0
++++*/
}|code-block|syntax|javascript|127270|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

why not use Swift's native types directly?

<pre><code>import Foundation

struct Usage {
 var totalData: Double = 0
 var remainingTotalData: Double = 0

 init(jsonData: NSData) {
 do {
 if let jsonDict = try NSJSONSerialization.JSONObjectWithData(jsonData, options: []) as? [String:Double] {
 totalData = jsonDict["totalfup"] ?? 0
 remainingTotalData = jsonDict["totalrem"] ?? 0
 }
 } catch {
 print("Error occurred parsing data: \(error)")
 }
 }
}

if let data = "{\"totalfup\":96.340899,\"totalrem\":3548710948}".dataUsingEncoding(NSUTF8StringEncoding) {
 let usage = Usage(jsonData: data)
 dump(usage)
 /*
 ▿ Usage
 - totalData: 96.340899
 - remainingTotalData: 3548710948.0
 */
}
</code></pre>

blocks|key|126761|text|Swift+4|type|unstyled|depth|inlineStyleRanges|entityRanges|data|126762|++++let+strStatus:String+=+dictProperty.value(forKey:+"StatusType")+as!+String
++++let+myStatus+=+Double.init(strStatus)|code-block|syntax|javascript|126763|更新|126764|extension+String+{
++++func+toDouble()+->+Double?+{
++++++++let+numberFormatter+=+NumberFormatter()
++++++++numberFormatter.locale+=+Locale(identifier:+"en_US_POSIX")
++++++++return+numberFormatter.number(from:+self)?.doubleValue
++++}

++++func+toInt()+->+Int?+{
++++++++let+numberFormatter+=+NumberFormatter()
++++++++numberFormatter.locale+=+Locale(identifier:+"en_US_POSIX")
++++++++return+numberFormatter.number(from:+self)?.intValue
++++}

++++func+toFloat()+->+Float?+{
++++++++let+numberFormatter+=+NumberFormatter()
++++++++numberFormatter.locale+=+Locale(identifier:+"en_US_POSIX")
++++++++return+numberFormatter.number(from:+self)?.floatValue
++++}

++++func+toBool()+->+Bool?+{
++++++++let+numberFormatter+=+NumberFormatter()
++++++++numberFormatter.locale+=+Locale(identifier:+"en_US_POSIX")
++++++++return+numberFormatter.number(from:+self)?.boolValue
++++}
}|126765|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

<h1>Swift 4</h1>

<pre><code> let strStatus:String = dictProperty.value(forKey: "StatusType") as! String
 let myStatus = Double.init(strStatus)
</code></pre>

<h1>Update</h1>

<pre><code>extension String {
 func toDouble() -&gt; Double? {
 let numberFormatter = NumberFormatter()
 numberFormatter.locale = Locale(identifier: "en_US_POSIX")
 return numberFormatter.number(from: self)?.doubleValue
 }

 func toInt() -&gt; Int? {
 let numberFormatter = NumberFormatter()
 numberFormatter.locale = Locale(identifier: "en_US_POSIX")
 return numberFormatter.number(from: self)?.intValue
 }

 func toFloat() -&gt; Float? {
 let numberFormatter = NumberFormatter()
 numberFormatter.locale = Locale(identifier: "en_US_POSIX")
 return numberFormatter.number(from: self)?.floatValue
 }

 func toBool() -&gt; Bool? {
 let numberFormatter = NumberFormatter()
 numberFormatter.locale = Locale(identifier: "en_US_POSIX")
 return numberFormatter.number(from: self)?.boolValue
 }
}
</code></pre>

blocks|key|2683255|text|在Swift+5.0上进行了测试和工作。|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|2683256|我也有同样的问题。|2683257|这对我很有效。|2683258|//+check+dict["dummy"]+is+a+String+first
if+let+receivedData+=+(dict["dummy"]).doubleValue+{
++//+add+more+code+in+case+the+condition+is+true
}
else+{
+//+add+more+code+in+case+the+condition+is+false
}|code-block|syntax|javascript|2683259|当您想要比较接收到的数据或仅检查值时，它非常有用，如下面的示例所示。|2683260|let+receivedData+=+(results["data"]!).doubleValue

if+(receivedData+==+0){
++++++self.label.text+=+"Nothing+seem+to+be+added+yet!"
}|2683261|entityMap^0|0|K|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|X|8|@]|D|@]|E|$]]|$1|H|3|I|5|6|7|Y|8|@]|D|@]|E|$]]|$1|J|3|K|5|L|7|Z|8|@]|D|@]|E|$M|N]]|$1|O|3|P|5|6|7|10|8|@]|D|@]|E|$]]|$1|Q|3|R|5|L|7|11|8|@]|D|@]|E|$M|N]]|$1|S|3|-4|5|6|7|12|8|@]|D|@]|E|$]]]|T|$]]

Tested and Working for Swift 5.0.

I had the same problem.

This worked for me.

<pre><code>// check dict["dummy"] is a String first
if let receivedData = (dict["dummy"]).doubleValue {
 // add more code in case the condition is true
}
else {
 // add more code in case the condition is false
}
</code></pre>

It is really helpful when you want to compare the received data or just check the value like the following example.

<pre><code>let receivedData = (results["data"]!).doubleValue

if (receivedData == 0){
 self.label.text = "Nothing seem to be added yet!"
}
</code></pre>

blocks|key|126794|text|字符串插值|type|unstyled|depth|inlineStyleRanges|entityRanges|data|126795|我发布了my+answer+in+a+similar+thread。|offset|length|126796|if+let+jsonDict_any+=+jsonDict["totalfup"],+
+++let+jsonDict_double+=+Double("\(jsonDict_any)")+{
+++//..
}|code-block|syntax|javascript|126797|从本质上讲，这避免了必须尝试多个类型转换。通过首先检查它的存在，我们可以使用字符串插值，然后尝试将其转换为Double。|126798|警告：|126799|正如@Alexander指出的，此解决方案允许任何Type成为String并检查Double值。仅当您不关心插值之前的值的Type时，才使用此选项。|style|CODE|126800|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/a/68322463/8845253^0|0|4|T|0|0|0|0|0|P|4|V|6|14|6|1P|4|0^^$0|@$1|2|3|4|5|6|7|10|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|11|8|@]|9|@$D|12|E|13|1|14]]|A|$]]|$1|F|3|G|5|H|7|15|8|@]|9|@]|A|$I|J]]|$1|K|3|L|5|6|7|16|8|@]|9|@]|A|$]]|$1|M|3|N|5|6|7|17|8|@]|9|@]|A|$]]|$1|O|3|P|5|6|7|18|8|@$D|19|E|1A|Q|R]|$D|1B|E|1C|Q|R]|$D|1D|E|1E|Q|R]|$D|1F|E|1G|Q|R]]|9|@]|A|$]]|$1|S|3|-4|5|6|7|1H|8|@]|9|@]|A|$]]]|T|$U|$5|V|W|X|A|$Y|Z]]]]

<h2>String interpolation</h2>
I posted <a href="https://stackoverflow.com/a/68322463/8845253">my answer in a similar thread</a>.
<pre><code>if let jsonDict_any = jsonDict[&quot;totalfup&quot;], 
 let jsonDict_double = Double(&quot;\(jsonDict_any)&quot;) {
 //..
}
</code></pre>
Essentially, this avoids having to try multiple typecastings. By checking first for its existence, we can can then use string interpolation, then try casting it to a Double.
<h3>Warning:</h3>
As @Alexander pointed out, this solution allows any <code>Type</code> to become a <code>String</code> and be checked for a <code>Double</code> value. Only use this if you're not concerned about the value's <code>Type</code> prior to interpolation.

I have a Swift struct like this.

<pre><code>struct Usage {
 var totalData: Double
 var remainingTotalData: Double

 init(jsonData: NSData) {
 var jsonDict = [String: AnyObject]()

 do {
 jsonDict = try NSJSONSerialization.JSONObjectWithData(jsonData, options: []) as! [String: AnyObject]
 } catch {
 print("Error occurred parsing data: \(error)")
 }

 totalData = jsonDict["totalfup"] as! Double
 remainingTotalData = jsonDict["totalrem"] as! Double
 }
}
</code></pre>

From an API, I get the following JSON response. This is the println of the <code>jsonDict</code> variable.

<pre><code>[
 "totalfup": 96.340899, 
 "totalrem": 3548710948
]
</code></pre>

When I try to assign the value of the <code>totalfup</code> to the property <code>totalData</code>, I get this error.

Could not cast value of type 'NSTaggedPointerString' to 'NSNumber'

Anyone knows why? I tried changing the property type to <code>float</code> and then the whole struct to class but still the issue occurs.

Could not cast value of type 'NSTaggedPointerString' to 'NSNumber'

Swift

JSON

我有一个这样的Swift结构。struct Usage {    var totalData: Double    var remainingTotalData: Double    init(jsonData: NSData) {        var jsonDict = [String: AnyObject]()...

问无法将'NSTaggedPointerString‘类型的值强制转换为'NSNumber’
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