swift - JSONObjectWithData error : unexpectedly found nil while unwrapping an Optional value -

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this question has answer here:

hi i'm having problem nsjsonserialization reading json api

code: 

func json() {      let urlstr = "https://apis.daum.net/contents/movie?=\etc\(keyword)&output=json"      let urlstr2: string! = urlstr.stringbyaddingpercentencodingwithallowedcharacters(nscharacterset.urlhostallowedcharacterset())      let url = nsurl(string: urlstr2)       let data = nsdata(contentsofurl: url!)       {           let ret = try nsjsonserialization.jsonobjectwithdata(data!, options: nsjsonreadingoptions(rawvalue: 0)) as! nsdictionary           let channel = ret["channel"] as? nsdictionary          let item = channel!["item"] as! nsarray           element in item {          let newmovie = movie_var()           // etc           movielist.append(newmovie)     }       catch {     } }

and getting error 

let ret = try nsjsonserialization.jsonobjectwithdata(data!, options: nsjsonreadingoptions(rawvalue: 0)) as! nsdictionary

fatal error: unexpectedly found nil while unwrapping optional value

how fix it?

the return type of contentsofurl initializer of nsdata optional nsdata. 

let data = nsdata(contentsofurl: url!) //this returns optional nsdata

since contentsofurl initializer method returns optional, first need unwrap optional using if let , use data if not nil shown below.

if let data = nsdata(contentsofurl: url!) {     //also advised check whether can type cast nsdictionary using as?. if use as! force type cast , if compiler isn't able type cast nsdictionary give runtime error.     if let ret = try nsjsonserialization.jsonobjectwithdata(data, options: nsjsonreadingoptions(rawvalue: 0)) as? nsdictionary {       //do whatever want ret     } }

but in case of code snippet you're not checking whether data contentsofurl nil or not. you're forcefully unwrapping data , in particular case data nil unwrapping failing , giving error - unexpectedly found nil while unwrapping optional value.

hope helps.


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