I am trying to create a NSTimer so that I can move a UIImageView down but
The NSTImer is having difficulty, saying first that this.
var timer = NSTimer.scheduledTimerWithTimeInterval(0.5, target:self(), selector: Selector ("mrockdown"), userInfo: nil, repeats: true)
is missing argument for parameter #1 in call. But when I remove the brackets from the target:self() it tells me
Cannot invoke 'scheduledTimerWIthTimerInterval' with an argument list of type '(Double, target: ViewController -> () -> ViewController, selector: Selector, userinfo: nil, repeates Bool.
What should I do?
The problem has to do with where you are saying this. It looks like you are trying to say this as part of a property declaration:
class ViewController {
var timer = ...
// ...
}
But you can't do that, because there is no self as far as a stored property is concerned. You need to declare the timer as an Optional and then initialize it later:
class ViewController {
var timer = NSTimer!
func someMethod {
timer = ...
}
}
Then you will remove the parentheses (they are wrong) and everything will compile just fine.
You can do this inside the function where you want to trigger the timer (i.e. viewDidLoad or some IBAction)
_ = Timer.scheduledTimer(timeInterval: yourInterval, target: self, selector: #selector(yourFunction), userInfo: nil, repeats: true)
That being said, to animate a view you should use this instead:
UIView.animate(withDuration: yourDuration) {
// set yourView's final position here
}
Related
In my ViewController class, I have a function:
func updateTimes() {
// (code)
}
I create a timer:
class ViewController: NSViewController {
var timer = Timer.scheduledTimer(timeInterval: 5,
target: self,
selector:
#selector(ViewController.updateTimes),
userInfo: nil,
repeats: true)
The compiler is happy with this. At runtime, when the timer fires, I get an exception:
unrecognized selector sent to instance 0x6000000428b0
Am I doing something obviously wrong?
As I wrote as a comment on NaGib ToroNgo's answer, he has given us a nice suggestion.
The selector may not be sent to the instance of ViewController.
I guess the ViewController would be taking this form:
class ViewController: UIViewController {
var timer = Timer.scheduledTimer(timeInterval: 5,
target: self,
selector: #selector(ViewController.updateTimes),
userInfo: nil,
repeats: true)
//...(Other property declarations or method definitions)...
func updateTimes() {
// (code)
}
}
The variable timer is declared as an instance property, and self is used in an initial value of timer. (In some old versions of Swift, this sort of usage caused error, so I was thinking that this line exists in any of the methods.)
In the current version of Swift (tested with Swift 3.1/Xcode 8.3.3), the code above does not cause error, but self is interpreted as a method reference of self() method declared in NSObjectProtocol. So, Selector("updateTimes") is sent to the closure representing the method reference (curried function), not to the instance of the ViewController.
The closure does not have a method named updateTimes, which caused the exception:
unrecognized selector sent to instance
Move the initial value code into some instance context, and then self represents the instance of the ViewController:
class ViewController: UIViewController {
var timer: Timer? //<- Keep `timer` as an instance property, but move the initial value code into `viewDidLoad()`.
//...(Other property declarations or method definitions)...
override func viewDidLoad() {
super.viewDidLoad()
//Do initialize the timer in the instance context.
timer = Timer.scheduledTimer(timeInterval: 5,
target: self,
selector: #selector(self.updateTimes),
userInfo: nil,
repeats: true)
//...
}
//In Swift 3, `#objc` is not needed, just for a preparation for Swift 4
#objc func updateTimes() {
// (code)
}
}
I believe this does not cause unrecognized selector exception.
The code you have provided seems perfect. I think the problem is, somehow your view controller is getting released or having dangling pointer.
Its time to say good bye to selectors!!! use the below code
Timer.scheduledTimer(withTimeInterval: 5, repeats: true) { (timer) in
// check self for nil before using
}
I have the following instance method in my Swift class Sentence which makes a call to a NSTimer which calls the class instance method as its Selector. When I run the program without breakpoints, it gets to the first NSTimer successfully but then stalls at NSTimer. When I add a breakpoint to see if sentenceDidFinish is ever called, I see that it never is, proving it stops at the first NSTimer.
class Sentence : NSObject {
//init() etc.
func playEvent(eventIndex : Int){
if (eventIndex < 2){
let currEvent = self.eventArray[eventIndex]
currEvent.startEvent()
let nextIndex = eventIndex + 1
print("Play Event event id is ", eventIndex)
NSTimer.scheduledTimerWithTimeInterval(currEvent.duration, target: self, selector: Selector("playEvent:"), userInfo: NSNumber(integer: nextIndex), repeats: false)
}
else if (eventIndex==2){
self.eventArray[eventIndex].startEvent()
print("Play Event event id is ", eventIndex)
NSTimer.scheduledTimerWithTimeInterval(0.4, target: self, selector: Selector("sentenceDidFinish"), userInfo: nil, repeats: false)
}
else{
//DO Nothing
}
}
func sentenceDidFinish(){
//foo
//bar
}
}
Here is the full .swift file:
https://gist.github.com/anonymous/e0839eae1d77e1e4b671
When you call playEvent: with the timer, the argument passed will be the timer itself, not the integer. But in the declaration for eventIndex you are acting as if it will be the integer.
Try adding a method like this:
func handleTimer(timer: NSTimer) {
playEvent(timer.userInfo as! Int)
}
Then call the first timer like this:
NSTimer.scheduledTimerWithTimeInterval(0.4, target: self, selector: "handleTimer:", userInfo: NSNumber(integer: nextIndex), repeats: false)
The forced casting (as!) will crash if userInfo isn't castable to Int. Safer, but more verbose would look like:
func handleTimer(timer: NSTimer) {
guard let index = timer.userInfo as? Int else { return }
playEvent(index)
}
Just a simple task, but I'm in trouble. Trying to make a different way but it fails.
How to init NSTimer with declared previously variable? Neither var nor let helps.
The initial value of a property (in your case: timer) cannot depend on another property of the class (in your case: interval).
Therefore you have to move the assigment timer = NSTimer(interval, ...) into a method of the
class, e.g. into viewDidLoad. As a consequence, timer has to be defined as an
optional or implicitly unwrapped optional.
Note also that Selector(...) takes a literal string as argument, not the method itself.
So this should work:
class ViewController: UIViewController {
var interval : NSTimeInterval = 1.0
var timer : NSTimer!
func timerRedraw() {
}
override func viewDidLoad() {
super.viewDidLoad()
timer = NSTimer(timeInterval: interval, target: self, selector: Selector("timerRedraw"), userInfo: nil, repeats: true)
// ...
}
// Other methods ...
}
Try:
var interval:NSTimeInterval = 1.0
var timer = NSTimer.scheduledTimerWithTimeInterval(interval, target: self, selector: "timerRedraw:", userInfo: nil, repeats: true)
pro-tip and hopefully an appreciated FYI: Swift functions should also start with lower case letters (i.e. "timerRedraw").
Just a simple task, but I'm in trouble. Trying to make a different way but it fails.
How to init NSTimer with declared previously variable? Neither var nor let helps.
The initial value of a property (in your case: timer) cannot depend on another property of the class (in your case: interval).
Therefore you have to move the assigment timer = NSTimer(interval, ...) into a method of the
class, e.g. into viewDidLoad. As a consequence, timer has to be defined as an
optional or implicitly unwrapped optional.
Note also that Selector(...) takes a literal string as argument, not the method itself.
So this should work:
class ViewController: UIViewController {
var interval : NSTimeInterval = 1.0
var timer : NSTimer!
func timerRedraw() {
}
override func viewDidLoad() {
super.viewDidLoad()
timer = NSTimer(timeInterval: interval, target: self, selector: Selector("timerRedraw"), userInfo: nil, repeats: true)
// ...
}
// Other methods ...
}
Try:
var interval:NSTimeInterval = 1.0
var timer = NSTimer.scheduledTimerWithTimeInterval(interval, target: self, selector: "timerRedraw:", userInfo: nil, repeats: true)
pro-tip and hopefully an appreciated FYI: Swift functions should also start with lower case letters (i.e. "timerRedraw").
I have a timer calling a method that needs to have two references to other variables (gravity and player)
func update(inout gravity: CGVector, inout player: Player) {
timer = NSTimer.scheduledTimerWithTimeInterval(0.1, target: self, selector: Selector("myMethod"), userInfo: gravity, repeats: true) // Here I get the error: extra argument 'selector' in call
}
func myMethod() {
println(timer.userInfo.gravity.dx)
}
While the above works for contants or regular variables, when I try to pass a pointer or an inout variable I get the error "Extra argument 'selector' in call". How can I pass the references to the variables to myMethod?
Try it without the Selector:
timer = NSTimer.scheduledTimerWithTimeInterval(0.1, target: self, selector: "myMethod", userInfo: gravity, repeats: true)
This is the format that works for me. Also, in my tests, if you pass gravity as userInfo, and gravity as a memory property, you can access it like this:
func myMethod() {
println(timer.userInfo.memory)
}