unexpectedly found nil while unwrapping an Optional value - swift

I put the m3u8 in GCDWebServer to play. When I use Wi-Fi, it is no problem. But using 4G, appears this problem.


You are force unwrapping m3u8 in your code. If that's ever nil, you're going to have a problem. You're saying that it will never be nil when you force unwrap using that !.
You can use the if let approach, or you can test for nil too.
// Are you sure dataServer isn't nil too here?
if let serverAddress = dataServer!.serverURL.URLByAppendingPathComponent(self.m3u8) {
//Should be safe
}
Or
if m3u8 == nil {
print("m3u8 is nil")
return
}


I have already solved the problem.When I use 4 g, access to the dataServer!ServerURL is nil.My solution is to give it a local IP
if davServer?.serverURL == nil {
serverAddress = NSURL.init(string: "http://localhost/playts.m3u8")!
}else{
serverAddress = (davServer?.serverURL.URLByAppendingPathComponent(self.m3u8!))!
}

Related

How to read null values from SQLite database using Swfit [duplicate]

I am reading from a dbtable and get an error at a specific position of the table. My sql is ok, because I could already read from the same table, but at a specific row I get an error and I would like to know howto handle this error. I am not looking for a solution to solve my db-issue, I am just looking for handling the error, so it doesn't crash.
I have the following code :
let unsafepointer=UnsafePointer<CChar>(sqlite3_column_text(statement, 2));
if unsafepointer != nil {
sText=String.fromCString(unsafepointer)! // <<<<<< ERROR
} else {
sText="unsafe text pointer is nil !";
}
I get an error:
"fatal error: unexpectedly found nil while unwrapping an Optional value"
at line marked with <<<<<< ERROR.
The unsafe pointer's value is not nil:
pointerValue : 2068355072
How can I handle this error, so my app is not crashing ?

Another possible solution is this:
let unsafepointer=UnsafePointer<CChar>(sqlite3_column_text(statement, 2));
var sText = "unsafe text pointer is nil !";
if unsafepointer != nil{
if let text = String.fromCString(unsafepointer) as String?{
sText = text;
}
}

let statementValue = sqlite3_column_text(statement, 2)
var sText = withUnsafeMutablePointer(&statementValue) {UnsafeMutablePointer<Void>($0)}

if sqlite3_column_text(statement, 2) != nil {
print("do something")
} else {
YourString = ""
}

Swift 4 - Catch Error if Value not in Plist

I have this code
let path = self.userDesktopDirectory + "/Library/Preferences/.GlobalPreferences.plist"
let dictRoot = NSDictionary(contentsOfFile: path)
if let dict = dictRoot{
try print(dict["AppleLocale"] as! String)
}
If the Value "AppleLocale" didnt exists the script crashes. What I must add to "catch" the Error and avoid the crash?

If the Value "AppleLocale" didnt exists the script crashes. What I
must add to "catch" the Error and avoid the crash?
depends on what's the reason for causing the crash. Mentioning that "If the Value AppleLocale didnt exists" means the the reason for the crash would be the force casting:
dict["AppleLocale"] as! String
probably, it has nothing to do with the try, it would be:
Unexpectedly found nil while unwrapping an Optional value
Means that at some point dict["AppleLocale"] could be nil or even if it contains a value as not a string it will crash (optional). You have to make sure that dict["AppleLocale"] is a valid (not nil) string, there are more than just one approach to follow for doing it, for instance you could do optional binding, like this:
let path = self.userDesktopDirectory + "/Library/Preferences/.GlobalPreferences.plist"
let dictRoot = NSDictionary(contentsOfFile: path)
if let dict = dictRoot{
if let appleLocale = dict["AppleLocale"] as? String {
print(appleLocale)
} else {
// `dict["AppleLocale"]` is nil OR contains not string value
}
}
Actually, I would assume that you don't have to deal with try for such a case.

getting "unexpectedly found nil" AFTER performing nil check

Despite checking for nil, I am getting fatal error: unexpectedly found nil while unwrapping an Optional value the error is being caught in the conditional (first line below)
if (obj.prop != nil && obj.prop?.otherprop != nil) {
anotherObj.yetanotherprop = (obj.prop?.otherprop as NSURL).absoluteString
}
I have also tried this with if let as follows (xcode highlights the 2nd let as being where the unexpected nil is found):
if let objA = obj.prop,
let otherProp = objA.otherPROP {
anotherObj.yetanotherprop = (otherProp as NSURL).absoluteString
}
Why don't either of these work?!
I am getting the source object (obj in both cases above) from a 3rd party library that is written in objective c. I am suspecting that I am checking for nil wrong somehow?

So in writing this up I think I sort of figured it out. I don't knwo why the first one doesn't work, but the second works as:
if let objA = obj.prop,
let otherProp = objA?.otherPROP {
anotherObj.yetanotherprop = (otherProp as NSURL).absoluteString
}

Swift, print issue when use ? and ! variables [duplicate]

This question already has answers here:
What does "Fatal error: Unexpectedly found nil while unwrapping an Optional value" mean?
(16 answers)
Closed 6 years ago.
I got access error('fatal error: unexpectedly found nil while unwrapping an Optional value') when print variable p02. According to the error message, I still cannot understand the reason.
var p02:Person! = nil
var p03:Person? = nil
if (p02==nil)
{
print("p02 is nil")
}
if (p03==nil)
{
print("p03 is nil")
}
print(p03)
print(p02)
Anyone know why,
Thanks

cause it always tries to print p02 and p03 even if they are nil
try this
var p02:Person! = nil
var p03:Person? = nil
if (p02==nil)
{
print("p02 is nil")
}else{
print(p02)
}
if (p03==nil)
{
print("p03 is nil")
}else{
print(p03)
}

unexpectedly found nil while unwrapping an Optional value while reading from DS with fromCString

I am reading from a dbtable and get an error at a specific position of the table. My sql is ok, because I could already read from the same table, but at a specific row I get an error and I would like to know howto handle this error. I am not looking for a solution to solve my db-issue, I am just looking for handling the error, so it doesn't crash.
I have the following code :
let unsafepointer=UnsafePointer<CChar>(sqlite3_column_text(statement, 2));
if unsafepointer != nil {
sText=String.fromCString(unsafepointer)! // <<<<<< ERROR
} else {
sText="unsafe text pointer is nil !";
}
I get an error:
"fatal error: unexpectedly found nil while unwrapping an Optional value"
at line marked with <<<<<< ERROR.
The unsafe pointer's value is not nil:
pointerValue : 2068355072
How can I handle this error, so my app is not crashing ?

Another possible solution is this:
let unsafepointer=UnsafePointer<CChar>(sqlite3_column_text(statement, 2));
var sText = "unsafe text pointer is nil !";
if unsafepointer != nil{
if let text = String.fromCString(unsafepointer) as String?{
sText = text;
}
}

let statementValue = sqlite3_column_text(statement, 2)
var sText = withUnsafeMutablePointer(&statementValue) {UnsafeMutablePointer<Void>($0)}

if sqlite3_column_text(statement, 2) != nil {
print("do something")
} else {
YourString = ""
}