如何查询并将Parse.com日期转换为NSDate/String [英] How to query and convert Parse.com Date to NSDate/String
问题描述
我要获取解析列"createdAt"，对其进行查询并使其成为一个字符串，该字符串作为标签显示在UI上，以向用户显示产品何时发布以及何时过期.
I want to take the parse column "createdAt", query it and make it into a string that displays on the UI as a label to show the user when a product was posted and when it expires.
关于stackoverflow也有类似的问题，但是没有一个问题对我有帮助，所有人都给了我错误和崩溃的信息.
There are similar questions on stackoverflow, but none have helped me and all have given me errors and crashes.
我正在使用TableViewController类，正在查询两件事:productName和timeCreated. (productName我可以毫无问题地显示在单元格中.)
I am using a TableViewController class and I'm querying 2 things: the productName and the timeCreated. (The productName I'm able to display in a cell without a problem.)
我尝试了几种获取日期的方法:
I've tried several ways of getting the date:
这是第一种方法.我尝试用另一个Parse对象查询它:
Here is the first way. I tried querying it WITH the other Parse object:
var productName = [String]()
var timeCreated = [NSDate]()
//Arrays above the viewDidLoad() to store the productName and the timeCreated
override func viewDidLoad() {
super.viewDidLoad()
var query = PFQuery(className: "ProductInfo")
query.findObjectsInBackgroundWithBlock ({ (objects, error) -> Void in
if let objects = objects {
self.productName.removeAll(keepCapacity: true)
self.timeCreated.removeAll(keepCapacity: true)
for object in objects {
self.productName.append(object["pName"] as! String)
self.timeCreated.append(object["createdAt"] as! NSDate)
print(self.productName)
print(self.timeCreated)
self.tableView.reloadData()
}
}
})
}
我尝试的第二种方法是使用此代码与productName对象单独进行查询.最终将其格式化，然后使用stringFromDate将其转换为字符串.我没有将其放入数组中，但是我假设如果我想使用它，我也应该这样做?这是我尝试但没有帮助的链接:如何将解析日期对象转换为字符串?像这样:
The second way I'm trying is to query it separately from the productName object on its own, using this code. Ultimately formatting it, and then converting it into a string with stringFromDate. Im not putting it into an array, but I'm assuming I should as well if i want to use it?? This is the link I tried but didn't help: How to convert a parse date object to a string? Like this:
var dateQuery = PFQuery(className:"ProductInfo")
dateQuery.findObjectsInBackgroundWithBlock ({ (objects, error) -> Void in
if let objects = objects {
for object in objects {
var createdAt = object["createdAt"]
if createdAt != nil {
let dateFormatter = NSDateFormatter()
dateFormatter.dateFormat = "yyyy'-'MM'-'dd'T'HH':'mm':'ss.SSS'Z'"
let date = dateFormatter.stringFromDate(createdAt as! NSDate)
print(date)
}
}
}
})
这也在viewDidLoad方法中，但仅在第一个查询下方.
This is also in the viewDidLoad method, but just below the first query.
我遇到的错误是:fatal error: unexpectedly found nil while unwrapping an Optional value两种方式.
The error I'm getting is this: fatal error: unexpectedly found nil while unwrapping an Optional value for both ways.
它以我尝试的第一种方式突出显示了这一行:
self.timeCreated.append(object["createdAt"] as! NSDate)
It highlights this line in the first way I tried:
self.timeCreated.append(object["createdAt"] as! NSDate)
这是我做第二种方法的这一行:
let date = dateFormatter.stringFromDate(createdAt as! NSDate)
and this line for the 2nd way I did it:
let date = dateFormatter.stringFromDate(createdAt as! NSDate)
为什么给我一个错误?关于谁可以查询并将其转换为我可以使用的字符串(在数组中)的任何想法?
Why is it giving me an error? Any ideas on who to query it and convert it into a string (in an array) that I can use?
任何帮助将不胜感激.
Any help is greatly appreciated.
推荐答案
在日期创建的就像PFObject的私有参数一样，因此您应该使用提供的访问器函数，而不要像普通容器那样尝试访问它.因此，将代码更改为:
The created at date is like a private parameter of the PFObject, so you should use the accessor function provided rather than try to access it like a generic container. So, change your code to:
self.timeCreated.append(object.createdAt as NSDate)
这篇关于如何查询并将Parse.com日期转换为NSDate/String的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
