json.swift 错误是 Self.init 未在委托初始化程序的所有路径上调用

Question

enter image description here

errors such as the photo came out in json.swift

I don't know how to fix it. please help me

    public convenience init(nsurl:NSURL) {
    var enc:NSStringEncoding = NSUTF8StringEncoding
    let err:NSError?

    do {
        let str: String? = try NSString(contentsOfURL: nsurl, encoding: NSUTF8StringEncoding) as String
        //print(str)

        self.init(nsurl:nsurl)

    } catch let error as NSError {
        //print(error.description)

    }
}

Answer 1

You have a few options here depend on your intention.

If you just wont your object to be crated and print addition info during init you can rewrite you code like this.

public convenience init(nsurl:NSURL) {       
 var enc:NSStringEncoding = NSUTF8StringEncoding
 let err:NSError?

 self.init(nsurl:nsurl)
 do {
       let str: String? = try NSString(contentsOfURL: nsurl, encoding: NSUTF8StringEncoding) as String
       print(str)

    } catch let error as NSError {
       print(error.description)
    }
}

Another option is to have failable initializer. For this you need call self.init(nsurl:nsurl) if do block performed without exception otherwise return nil from catch block. Also you need to mark you convenience init method as failable (see "?" after init word)

public convenience init?(nsurl:NSURL) {       
 var enc:NSStringEncoding = NSUTF8StringEncoding
 let err:NSError?

    do {
       self.init(nsurl:nsurl)
       let str: String? = try NSString(contentsOfURL: nsurl, encoding: NSUTF8StringEncoding) as String
       print(str)

    } catch let error as NSError {
       print(error.description)
       return nil
    }
}