I am trying to create a very simple app as I am new to swift. I am trying to make an app where there are four textfields, someone can put in words in each of the text fields and it picks one of them at random. However I am getting the error: 'Cannot assign value of type 'Int' to type 'String?'.
As Leif answered, "(\randomIndex)" will let you print the index you generated. If you want to print the actual text for the text field though...
let randomTextField = array[randomIndex]
label.text = randomTextField.text
let randomIndex = arc4random_uniform(4)
label.text = "\(yourArrayOfStrings[randomIndex])"
Either put the Int value as "\(index)" or String(index)
Related
I have an array of dictionaries ([[Double:Double]]) which I want to convert into a Set of dictionaries. My goal is to use the .symmetricDifference to find the differences between two arrays (both are of type [[Double:Double]]). How can I do this?
I found this on hackingwithswift.com and tried to use it but I am getting this error:
Type '[[Double : Double]]' does not conform to protocol 'Hashable'
I have also tried this code...
let array1:[[Double:Double]] = [[4.5:3.678], [6.7:9.2867], [7.3: 8.7564]]
let array2:[[Double:Double]] = [[4.5:3.678], [6.7:9.2867]]
let array3 = Set<[[Double:Double]]>(array1).symmetricDifference(Set(array2)) //On this line I get the error above.
You don't want a Set of [[Double:Double]]. You want a Set of [Double:Double], because those are the objects in the array and you want them to be the objects in the Set.
Thus the right thing will happen if you simply say
let array1:[[Double:Double]] = [[4.5:3.678], [6.7:9.2867], [7.3: 8.7564]]
let set1 = Set(array1)
and so on.
This might require you to update to a newer version of Swift. It works in Swift 4.2.
I am asking this hesitantly as I know this is probably a dumb question.
I am returning a Realm result and then have gone ahead and tried to cast it to a String as normal (to put in a text label).
However I'm getting an error 'init' has been renamed to 'init(describing:)'.
When I try use the describing method instead, the label prints "Optional" inside it which obviously isn't what I want.
Is there a reason I can't use :
previousTimeLabel.text = String(lastRecord?.time)
I'm sure I've done this before and it's been fine, am I missing something? (lastRecord.time is an Int).
I've checked the answer here about Interpolation Swift String Interpolation displaying optional? and tried changing to something like this :
if let previousRounds = String(lastRecord?.rounds) {
previousRoundsLabel.text = previousRounds
}
but get the same error + Initializer for conditional binding must have Optional type, not 'String'
The issue isn't String(lastRecord?.time) being Optional. The issue is lastRecord being Optional, so you have to unwrap lastRecord, not the return value of String(lastRecord?.time).
if let lastRecord = lastRecord {
previousRoundsLabel.text = "\(lastRecord.time)"
}
To summarize Dávid Pásztor's answer, here's a way you can fix it:
previousTimeLabel.text = String(lastRecord?.time ?? 0)
This may not be the best way for your application. The point Dávid was making is that you need to deal with lastRecord possibly being nil before trying to pass its time Int into the String initializer. So the above is one simple way to do that, if you're ok with having "0" string as your previousTimeLabel's text if there was no lastRecord.
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'm new to coding and picked up some open source project to get the idea.
I'm getting the error:
Ambiguous reference to member 'subscript'
in the code below:
let pictures = ( selectedRestaurant["Pictures"] as! NSArray ) // Error
let picture = ( pictures[zoomedPhotoIndex] as! NSDictionary )
let pictureURL = picture["url"] as! String
let imageURL = NSURL(string: pictureURL)
let urlRequest = NSURLRequest(URL: imageURL!)
NSURLConnection.sendAsynchronousRequest(urlRequest, queue: NSOperationQueue.mainQueue()) {
response, data, error in
if error == nil && data != nil {
self.imageView.image = UIImage(data: data!)
self.imageView.contentMode = UIViewContentMode.ScaleAspectFit
}
}
Just specify explicitly what is the type of pictures:
So instead of:
let pictures = selectedRestaurant["Pictures"] as! NSArray
Write:
let pictures: NSArray = selectedRestaurant["Pictures"] as! NSArray
For me the answer was to specifically state the type of array I was casting to:
if let foo = dictionary["bar"] as? [String]
It means that "Pictures" is not a valid subscript. It looks like you are creating a constant named pictures and you are trying to assign it a value of selectedRestaraunt["Pictures"] and then trying to cast it as an NSArray. If selectedrestaraunt is already an array, then what goes in the [] brackets after selectedRestaraunt should be an integer value which will refer to an index in the selectedRestaraunt array. Obviosuly "Pictures" is not an integer, it is a string.
If you are trying to access an array within an array. Meaning that Pictures is an array stored within the selectedRestarauntarray then you can access it by using selectedRestaraunt[index of Pictures array] where [index of pictures array] is an integer which is equal to the index number in which the Picutres array resides within the selectedRestaraunt array
I managed to get this error in a somewhat weird way. I had code like this:
cell.textLabel = anArrayOfStrings[indexPath.item].uppercased()
And I was stumped as to why it couldn't figure out that this was an array, even though I very clearly declared its type. I broke the line in two and finally got a helpful error message:
let name = anArrayOfStrings[indexPath.item].uppercased()
cell.textLabel = name
I was trying to assign a String to a UILabel, but somehow the point at which the type inference engine failed was at the subscript.
So my advice to anyone stumped by this is to try to break up your statement into bite-sized chunks that the Swift type inference engine can more easily digest.
As Eric and Eugene mentioned in their comments it is impossible to review the issue you are having without knowing the selectedRestaurant type. That is after all why you are getting the compiler ambiguity error.
I have to respectfully disagree with MikeG though. The problem is not one of a valid subscript. You'd be getting that kind of error, if for example you had a selectedRestaurant type of [NSNumber:AnyObject], where clearly String is no longer valid since the dictionary key could only be an NSNumber.
In my app I have got two textfields, one label and one button. I managed to get the content of the one textfield to be displayed in the label, but I want to display the content of both of the textfields.
#IBAction func buttonPushed(sender: UIButton) {
Label.text = "\(textfield1.text)"
+ "\(textfield2.text)"
The code above is the closest I´ve come, but the Label displays:
Optional"whatever I typed in the textfield"Optional"whatever I typed
in the textfield"
You have to unwrap the text
Label.text = textfield1.text! + textfield2.text!
You are concatenating strings, not adding numbers. In order to add the values, you need to cast the textfield value to a number like:
field.text!.toInt()
the ! unwraps the value to remove the "Optional". and toInt() casts a string (text) to and integer.
In the end, you code will look something like this:
#IBAction func buttonPushed(sender: UIButton) {
Label.text = "\(textfield1.text!.toInt())"
+ "\(textfield2.text!.toInt())"