let address = "http://www.example.com/?cevent=imt%2Fguide%252525252525252F"
let address2 = "http://www.example.com/?cevent=imt%2Fguide%2525252525252521"
let bodyString=NSMutableString()
bodyString.appendFormat("\(address)")
when I test in playground, the code errors, but when I use
bodyString.appendFormat("\(address2)")
it works! Why?
The runtime error.
You're calling appendFormat but you're not using any formatter string.
It should be used like this, with a formatter as the first argument (here the normal text formatter):
bodyString.appendFormat("%#", address)
Related
So I tried running our app with "Address Sanitizer" enabled. And I got this crash:
let sData = "-e5069fba-3612".data(using:String.Encoding.utf8)!
var pointer = sData.withUnsafeBytes {(bytes: UnsafePointer<CChar>) -> UnsafePointer<CChar> in
return bytes
}
pointer = pointer.advanced(by: 1)
let tmpPIN = String(cString: pointer)
print(tmpPIN)
the crash points to let tmpPIN = String(cString: pointer). Does anyone know the reason behind this? I can't figure out why this is happening.
Note, the app runs fine when I disabled the "Address Sanitizer". Should I be worry about this or just ignore it?
It seems you found an answer that works, but I'm adding one because I'm still kind of baffled by such complex code for such a simple problem.
Your code:
Transforms a Swift string to a Data object,
Gets unsafe bytes from that
Does pointer math on the unsafe bytes to move ahead one byte,
Finally converts the result back into a String.
Your fix makes it even more complex by appending an extra byte you don't even want (it works because C strings are expected to have a null character at the end, and your fix adds that).
This could be done far more simply as:
let sData = "-e5069fba-3612"
let tmpPIN = sData2.dropFirst()
The result is exactly the same.
Or you could handle multiple - characters at the start with something like
let tmpPIN = sData.drop { $0 == "-" }
Which gives the same result for this string.
I found this thread... When I add sData.append(0) after I initialize the sData the Address Sanitizer error is gone.
I'm receiving a compiler error and I'm not really sure why. I'm sure there is a simple answer for this. I have a core data attribute I'm trying to assign before saving. In my Core Data Property file it's defined as this:
#NSManaged public var age: Int32
I am using a UIPicker to select it and put it into an inputView. That works fine, so ageTextField: UITextField! holds the value. As I try to assign this to the CoreData object just before saving I get the following
person.age = ageTextField.text -> Cannot assign String? to Int32.
Ok, I understand that, so I cast it
person.age = Int(ageTextField.text) -> Value of Optional String not unwrapped...
Ok, I get that, so I unwrapped it, it asks to unwrap again and I agree:
person.age = Int(ageTextField.text!)! -> Type of expression is ambiguous without more context
I'm not sure what is wrong here, just looking over some old Swift 2 code of mine and this worked. This is my first code with Swift 3 though.
That compiler error is obscure at best and misleading at worst. Change your cast to Int32:
person.age = Int32(ageTextField.text!)!
Also: unless you are absolutely sure that the user will always enter a valid number into the textfield, use optional binding instead of force unwrap:
if let text = ageTextField.text,
let age = Int32(text)
{
person.age = age
}
The immediate issue is the use of the wrong type. Use Int32, not Int. But even once that is fixed, you have lots of other issues.
You should safely unwrap the text and then the attempt to convert the string to an integer.
if let text = ageTextField.text, let num = Int32(text) {
person.age = num
}
The use of all of those ! will cause a crash if the text is nil or it contains a value that isn't a valid number. Always use safe unwrapping.
Just make sure to unwrap the optional before convert. Make your code safe.
I am trying to find a count of entities which satisfy predicate. According to documentation and "header" files, this should work:
let fetch = NSFetchRequest<NSFetchRequestResult>(entityName: "FileRecord")
let ctx: NSManagedObjectContext = GetCtx()
let res = try ctx.count(for: fetch)
however I get compile error:
Cannot invoke 'count' with an argument list of type '(for: NSFetchRequest<NSFetchRequestResult>)'
however when I create the fetch request from FileRecord like this instead:
let fetch: NSFetchRequest<FileRecord> = FileRecord.fetchRequest()
I get the following error:
Cannot convert value of type 'NSFetchRequest<FileRecord>' to expected argument type 'NSFetchRequest<NSFetchRequestResult>'
Please anyone got an idea what can be wrong? I am a decent C++ language lawyer but I am just a novice with Swift...
EDIT: SOLVED
My example above was wrong. In reality I had code functionally identical to:
let res: UInt64 = try ctx.count(for: fetch)
since count returns Int, the function did not match. The error message was not specific enough for me to see it immediately. Thanks to all who have tried to help :)
I am trying to build a table of current locale properties in code, and have encountered issues with trying to pass the value of a variable to a function:
let currentLocale = Locale(identifier: "en_US")
let calendar1 = currentLocale.calendar // "gregorian (fixed)"
let propertyName = "calendar"
let calendar2 = currentLocale.propertyName // Error: Value of type 'Locale' has no member 'porpertyName'
In the last line of code above, the instance of Locale thinks I am passing it "propertyName" rather than the contents of the variable "calendar".
Is there any way to pass the value of propertyName ("calendar") to the instance of Locale? I know that in other languages, you can prepend the variable name like '$propertyName', and that tells it to read the value of the variable.
I want to keep this pure Swift if possible.
You are looking for some form of key-value coding.
It's a little tricky, in that this is a purely Objective-C feature of Cocoa, so it doesn't work with the Swift overlay class Locale; you will have to cast currentLocale to Objective-C NSLocale. Moreover, NSLocale exposes its attributes through special NSLocale.Key types. After a great deal of casting, I find that this works:
let calendar2 =
(currentLocale as NSLocale).object(forKey:NSLocale.Key(rawValue:propertyName))
calendar2 is typed as Any but you can cast it down to a String.
I'm trying to call substringWithRange on an option String but after multiple experiments am still not able to get it to compile:
var mdn:String?
var subscriber = CTSubscriber()
var carrierToken = subscriber.carrierToken
mdn = NSString(data:carrierToken, encoding:NSUTF8StringEncoding)
let range:NSRange = NSRange(location: 0, length: 10)
if mdn
{
let subString = mdn!.substringWithRange(range)
}
This will result in the compilation error saying the value of the optional NSString is not unwrapped.
I thought it already was unwrapped due to the !.
If I remove ! then I get an error saying String? does not have a member named substringWithRange.
Replace
var mdn:String?
with
var mdn:NSString?
You are using the var to store a NSString so you should give it the correct type. Although String and NSString are mutually assignable, it's not the same type.
String doesn't have the substringWithRange method.
I think this might actually be a compiler bug. I would report it to Apple and see how they come back.
However, the proper approach to unwrapping an optional for use if you need to gain some information from it. (Like obtaining a substring, in your example) is:
if let theMdn = mdn {
let subString = theMdn.substringWithRange(range)
}
That way your codeblock will only be executed if the unwrapping was successful.
Edit: Sulthan's answer might be more accurate. However I still think if you can unwrap the optional in a let block, you should be able to do it manually.