Question

我有来自Json的数据，并使用alamofireImage在UIImage中填充它。我从Json回来的其中一个元素是一个String，它有一个图像的URL。如果特定的Json字符串为null或空白，则会出现以下错误：

致命错误：索引超出范围

EventEngine.getEventGalery(invitedID, limit: "2") { (result, error) in
    DispatchQueue.main.async(execute: { () -> Void in

        if let response = result as? EventGaleryResponse{

            self.galery = response.data!

            let jsonDict = self.galery
            print("jsonDict \(jsonDict![0].photo!)")
            if jsonDict![0].photo != nil {
                self.imagearry1.af_setImage(withURL: URL(string: jsonDict![0].photo!)!)
            }
            if jsonDict![1].photo != nil {
                self.imagearry2.af_setImage(withURL: URL(string:jsonDict![1].photo!)!)
            }
            if jsonDict![2].photo != nil {
                self.imagearry3.af_setImage(withURL: URL(string: jsonDict![2].photo!)!)
            }
        }
    })
}

Answer 1

请勿在未经检查的情况下使用!运营商。我真的建议改为使用if let构造。

一些伪代码（我不知道你的类型）：

EventEngine.getEventGalery(invitedID, limit: "2") { (result, error) in
    DispatchQueue.main.async(execute: { () -> Void in

        if let response = result as? EventGaleryResponse{

            self.galery = response.data!

            let jsonDict = self.galery

            if let dict = jsonDict {
                setPhotoFromDict(dict, 0, self.imagearry1)
                setPhotoFromDict(dict, 1, self.imagearry2)
                setPhotoFromDict(dict, 2, self.imagearry3)
            } else {
                print("cannot deserialise \(String(describing: jsonDict)")
            }
        }
    })
}

private func setPhotoFromDict(<#DictType#> dict, Int index, <#ImageArrayType#> imageArary) {
    if let photo = dict[index].photo as? String, let url = URL(string: photo) {
        imageArary.af_setImage(withURL: url)
    }
}

初始错误来自此行print("jsonDict \(jsonDict![0].photo!)")，我想，因为你没有检查就访问了对象

Answer 2

我认为，你没有检查它是否为空

EventEngine.getEventGalery(invitedID, limit: "2") { (result, error) in
            DispatchQueue.main.async(execute: { () -> Void in

                if let response = result as? EventGaleryResponse{

                    self.galery = response.data!

                    let jsonDict = self.galery

                   if jsonDict != nil {

                    if jsonDict.count > 0 && jsonDict![0].photo != nil {
                        self.imagearry1.af_setImage(withURL: URL(string: jsonDict![0].photo!)!)
                    }
                    if jsonDict.count > 1 && jsonDict![1].photo != nil {
                        self.imagearry2.af_setImage(withURL: URL(string:jsonDict![1].photo!)!)
                    }
                    if jsonDict.count > 2 && jsonDict![2].photo != nil {
                        self.imagearry3.af_setImage(withURL: URL(string: jsonDict![2].photo!)!)
                    }

                  }
                }
            })
        }

索引超出范围数据nil swift 3

2 个答案: