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[英]How can I fix this "Fatal Error: unexpectedly found nil while unwrapping optional value"?
[英]Why do I get the following error: “fatal error: unexpectedly found nil while unwrapping an Optional value”? - and how can I fix it specifically?
這是我的代碼:
var usernames = [""]
var userids = [""]
var isFollowing = ["":false]
var refresher: UIRefreshControl!
func refresh() {
var query = PFUser.query()
query?.findObjectsInBackgroundWithBlock({ (objects, error) -> Void in
if let users = objects {
self.usernames.removeAll(keepCapacity: true)
self.userids.removeAll(keepCapacity: true)
self.isFollowing.removeAll(keepCapacity: true)
for object in users {
if let user = object as? PFUser {
if user.objectId != PFUser.currentUser()!.objectId {
self.usernames.append(user.username!)
self.userids.append(user.objectId!)
var query = PFQuery(className: "followers")
query.whereKey("follower", equalTo: PFUser.currentUser()!.objectId!)
query.whereKey("following", equalTo: user.objectId!)
query.findObjectsInBackgroundWithBlock({ (objects, error) -> Void in
if let objects = objects {
if objects.count > 0 {
self.isFollowing[user.objectId!] = true
} else {
self.isFollowing[user.objectId!] = false
}
}
if self.isFollowing.count == self.usernames.count {
self.tableView.reloadData()
self.refresher.endRefreshing()
}
})
}
}
}
}
})
我在這行上收到致命錯誤,它說:
query.whereKey(“ follower”,equalTo:PFUser.currentUser()!. objectId!)query.whereKey(“ following”,equalTo:user.objectId!)
我怎樣才能解決這個問題? 我搜索了其他幾篇文章,卻找不到有用的東西。 當您提供建議時,請非常具體-我是新手。
正如評論中所說,您的價值觀之一是零。
在查詢之前插入以下代碼,並修復返回nil的方法:
if (PFUser.currentUser() == nil) {
print("currentUser() is nil");
} else if (PFUser.currentUser()!.objectId == nil) {
print("PFUser.currentUser()!.objectId is nil");
} else if (user.objectId == nil) {
print("user.objectId is nil");
}
解析登錄肯定存在問題。在程序查詢期間是否要調用登錄功能? 並且您正在檢查結果變量嗎?
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