不能将 Nil 用于 PFObject 的键或值

Question

所以我有这个代码。

@IBAction func updateRatelabel(sender: AnyObject) {
    let rateValue = Int(rateSlider.value)
    if rateValue == 0 {
        rateLabel.text = "Budget (min.)"
    }
    else {
        rateLabel.text = "$ \(rateValue)"
    }
}

func createdoctor()
{
    let doctors =  PFObject(className: "doctors")
    if doctorName.text?.characters.count > 5 {
        doctorName.textColor = UIColor.redColor()   
    }
    else {
        let currentUser  = String( PFUser.currentUser())

        let rateValue =  rateLabel.text
        let rateValueInt = String(rateValue?.characters.dropFirst(2))
        print(rateValueInt)

        doctors["doctorName"] = doctorName.text
        doctors["Rate"] = Int(rateValueInt)
        doctors["doctorContent"] = doctorDetails.text
        doctors["createdby"] = currentUser
        doctors.saveInBackgroundWithBlock ({(success: Bool, error: NSError?) -> Void in
            if error == nil {
                print("created doctor")
            }
            else {
                print("image \(error)")
            }
            let alert = UIAlertController(title: "Success", message: "New doctor Created" , preferredStyle: UIAlertControllerStyle.Alert)
            alert.addAction(UIAlertAction(title: "Ok", style: UIAlertActionStyle.Default, handler: nil))
            self.presentViewController(alert, animated: true, completion: nil)

        })
    }
}

此代码启动时出现错误，这是正在发生的错误

> 016-01-31 01:00:07.921 idoctortwo[3294:151254] Attempting to load the
> view of a view controller while it is deallocating is not allowed and
> may result in undefined behavior (<UIAlertController: 0x7f8258c8af80>)
> Optional(Swift.String.CharacterView(_core:
> Swift._StringCore(_baseAddress: 0x00007f8258c9b9c2, _countAndFlags: 4,
> _owner: Optional(Swift._HeapBufferStorage<Swift._StringBufferIVars, Swift.UInt16>)))) 2016-01-31 01:00:12.771 idoctortwo[3294:151254] ***
> Terminating app due to uncaught exception
> 'NSInvalidArgumentException', reason: 'Can't use nil for keys or
> values on PFObject. Use NSNull for values.'

我设法发现下面这行代码是罪魁祸首

doctors["Rate"] = Int(rateValueInt)

如果我这样做

doctors["Rate"] = rateValueInt

我没有错误，但我的 Parse 列是一个数字列，因此努力将其设为数字​​。

编辑

2016-01-31 03:58:11.222 iLegaltwo[3662:186816] 尝试加载 视图控制器在释放时的视图是不允许的，并且 可能导致未定义的行为 () 可选（Swift.String.CharacterView（_core: Swift._StringCore(_baseAddress: 0x00007fb2c3667472, _countAndFlags: 4, _owner：可选（Swift._HeapBufferStorage））））2016-01-31 03：58：30.728 iLegaltwo [3662：186900] [错误]：创建的密钥类型无效，应为 *_User，但得到了 字符串（代码：111，版本：1.12.0）图像可选（错误域=解析 Code=111 "创建的密钥类型无效，预期为 *_User，但得到了 string" UserInfo={code=111,temporary=0,error=key 类型无效 createdby，预期 *_User，但得到字符串， NSLocalizedDescription=key createdby 的无效类型，预期 *_User，但得到了字符串})

针对上述错误修改后编辑：

func createCase()
    {
          let cases =  PFObject(className: "Cases")
        if caseName.text?.characters.count > 5
        {

            caseName.textColor = UIColor.redColor()

        }
        else
        {

            let currentUser  = String( PFUser.currentUser())


            let rateValue =  rateLabel.text
            let rateValueInt = String(rateValue?.characters.dropFirst(2))
            print(rateValueInt)

        cases["CaseName"] = caseName.text
        cases["Rate"] = Int(rateValueInt) ?? Int(0)
        cases["CaseContent"] = caseDetails.text
            cases["createdby"] = currentUser
        cases.saveInBackgroundWithBlock ({(success: Bool, error: NSError?) -> Void in
            if error == nil
            {
                print("created case")
            }
            else
            {
                print("image \(error)")
            }
                self.performSelectorOnMainThread("success", withObject: nil, waitUntilDone: true)
        })
        }


    }

    func success() {
        let alert = UIAlertController(title: "Success", message: "New doctor Created" , preferredStyle: UIAlertControllerStyle.Alert)
        alert.addAction(UIAlertAction(title: "Ok", style: UIAlertActionStyle.Default, handler: nil))
        self.presentViewController(alert, animated: true, completion: nil)
    }

Answer 1

无法从后台线程触摸 UI

从主线程推送视图控制器。罪魁祸首：

saveInBackgroundWithBlock...
    self.presentViewController

解决方案

- use `performSelectorOnMainThread`
- use dispatch_async(dispatch_get_main_queue(), ^(void) { } })

示例

将警报创建替换为

self.performSelectorOnMainThread("success", withObject: nil, waitUntilDone: true)

并添加此方法：

func success() {
    let alert = UIAlertController(title: "Success", message: "New doctor Created" , preferredStyle: UIAlertControllerStyle.Alert)
    alert.addAction(UIAlertAction(title: "Ok", style: UIAlertActionStyle.Default, handler: nil))
    self.presentViewController(alert, animated: true, completion: nil)
}

Answer 2

字典键/值不能为 nil

Int("someString") 不返回 Int，而是返回可选的 Int?。

documentation 将这些访问器列为 数组访问器，而实际上，使用 key/value，它们应该被视为 字典访问器 .

因此，您应该将PFObject 视为字典包装器：不能为键或值传递 nil。您将 对象 存储在字典中，而不是可选项。

扭曲

Int(rateValueInt) 最终成为 Int?，因为 Int(rateValueInt) 转换。

解决方案

doctors["Rate"] = Int(rateValueInt) ?? Int(0)

这将显式替换 Int，以防 Int(rateValueInt) 无法解包。