I am trying to use swift's shouldPerformSegueWithIdentifier() method, but it accepts 2 arguments. These are (identifier: String!, sender:AnyObject)
My main goal is to execute the code when pressing a login button in my storyboard, and depending of a series of checks return TRUE or FALSE, depending if whether the correct username and password were provided. So here are my questions:
What am I supposed to use as the identifier? Apple's documentation it explains that the identifier is a string that identifies the triggered segue. So suppose that my segue had the name of loginSegueProcess. How could I use it in my ViewController tat is assigned to my UIView? The thing is that I declare the method in my code and it requires me to specify both arguments (identifier & sender). How could I provide the arguments?
Will this method actually fulfill my needs? By that I mean if it will indeed stop the segue transition whenever my Login button is clicked and depending on whether the correct credentials were provided it is going to take you to the next View or it will show, say for example, an AlertView.
Finally, I was thinking that the performSegueWithIdentifier(args) method would help me as well. Does anybody know the difference between them?
Thanks a lot in advance!
isn't it what you want to do?
override func shouldPerformSegueWithIdentifier(identifier: String!, sender: AnyObject!) -> Bool {
if identifier == "LoginSuccessSegue" { // you define it in the storyboard (click on the segue, then Attributes' inspector > Identifier
var segueShouldOccur = /** do whatever you need to set this var to true or false */
if !segueShouldOccur {
println("*** NOPE, segue wont occur")
return false
}
else {
println("*** YEP, segue will occur")
}
}
// by default, transition
return true
}
You may not invoke shouldPerformSegueWithIdentifier() method by yourself. It will be automatically called just before transition to the next view giving a chance to determine wether the transition should take place or. You may conditionally return YES/NO from this method. If your condition does't involve any sever call,a simple logical checking this method will be enough for you.
performSegueWithIdentifier() is used to invoke a segue programmatically. Consider the above case with a network call, you may return NO from shouldPerformSegueWithIdentifier() initially since authentication is going on. After getting the response from server if it success you can call the segue to execute with performSegueWithIdentifier (Here the identifier is the ID you have given in the storyboard). Before make sure you are supposed to return YES from shouldPerformSegueWithIdentifier().
Now a third case if your segue is connecting from the login button(You have to connect it from the controller itself). The checking of shouldPerformSegueWithIdentifier is no more required. You can just call the segue with performSegueWithIdentifier() after getting the success response from server
Related
Update: this problem is more focused now, and not on quite the same topic. I've asked this question as a follow-on
ORIGINAL QUESTION:
I am getting a crash on a subclassed WKWebView-provisioned app.
ProcessAssertion::acquireSync Failed to acquire RBS assertion 'ConnectionTerminationWatchdog' for process with PID=87121, error: Error Domain=RBSServiceErrorDomain Code=1 "target is not running or doesn't have entitlement com.apple.runningboard.assertions.webkit" UserInfo={NSLocalizedFailureReason=target is not running or doesn't have entitlement com.apple.runningboard.assertions.webkit}
The problem is, that I can't tell if this is related or not. The actual error on crash is
Thread 1: EXC_BAD_ACCESS (code=1, address=0xbdb2dfcf0470)
Which I was assuming was something running off the end of an array. This makes some sense: I'm selecting from a table that filters out some entries from the data source; but I've checked that carefully; there is no point when a row index greater than the actual rows is accessed (and yes, I'm accounting for the difference between count and index).
The main change here is that I previously had a UIView that acted as a container for a number of CAShapeLayers. I also wanted to overlay text view, but with the proviso that this be via a WKWebView. With two separate views, I would have to either have the CAShapeLayer objects in front of, or behind the WebView. I was seeking a fix to that.
What I have done is substitute a WKWebView for the original UIView. I can add the CAShapes to it, so it performs the original function. It also can, presumably, display the html. And the original suggestion in this answer to a question I asked is what I am working towards. The idea being that it would allow the effect sought, with shapes in front of or behind the html elements.
But the error is thrown after the DidSelect call on the table:
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
Tracker.track("getting row \(indexPath.row)")
let ptv = tableView as? NovilloTableView
if ptv!.uiType == .textTable {
let gp = Projects.currentProject?.getPaths(type: PaletteView.getCurrentPane())
GitPaths.currentGitPath = gp![indexPath.row]
NotificationCenter.default.post(name: NNames.updateWebText.nn(), object: nil)
return
}
let svgs = Projects.currentProject!.getPaths(type : PaletteView.getCurrentPane())
var gitPath = svgs[indexPath.row]
var gitPaths = GitPaths.getMediaBoundingBoxes(paths: [gitPath])
guard let pathArrays = gitPath.parseForRegBeziers() else { return }
let rslt = pathArrays.0
let regBeziers = pathArrays.1
gitPath.boundingBox = gitPath.getBoundsParamsForPaths(src: regBeziers.isEmpty ? rslt : regBeziers)
GitPaths.currentGitPath = gitPath
// Tracker.track("sending notification")
NotificationCenter.default.post(name: NNames.updateMedia.nn(), object: nil,
userInfo: ["path" : gitPath])
Tracker.track("completed didSelect")
return
}
In other words, the interaction has ended; but I get this crash, even though I can se that the expected result (the rendering of the shapes into the view) has been completed correctly. It seems to be happening right after everything has completed, and no amount of breakpoints has shown anything else to be happening.
This is confusing to me, and I have hit a limit on what I know how to do to dig further into this. Given the nature of web connections, I've wondered if it's some asynchronous issue that I can't debug sequentially; but that's guesswork without any direct evidence.
I suspect that there is a possible configuration problem with the WebView that shows up once I interact with it, by changing its contents. I'm not actually trying to get it to load anything when it crashes, it's only performing its original function as a container for the CAShapeLayers, so I'm confused.
The main view that contains the WKWebView (which is subclassed, to support a function to determine if it should display the web content, and which I've commented out), is set as the delegate for the WKWebView, and that seems to be fine, though there are no actual protocol functions added to that view, not sure if that matters.
The other detail is that the WebView when it does load web content is only loading local text, and not connected to any services. This testing is happening in the Simulator, and I've come across advice elsewhere to allow for background processes that include enabling Background Fetch, etc., but this has done nothing to change the situation...
EDIT: this is the extent of the configuration of the subclassed WKWebView: maybe this is the issue?
mediaDisplay = NovilloWebView()
mediaPane.addSubview(mediaDisplay)
mediaDisplay.navigationDelegate = self
mediaDisplay.uiDelegate = self
mediaDisplay.backgroundColor = .clear
I have in two views that are connected to the menu, in one view I have a text field to enter your e-mail and I want to take that textfield text (that is the email address) to the other view, but I think I need to save that data to the phone so later when the user start the app again he/she will never have to type that address again, and then use that email address in the other view that will send an email to that address. Here is the code that I have:
let configCorreo = ConfigurarCorreo()
let mail = configCorreo.textField.text!
And then I set the recipient using that mail the user typed in the other viewController:
let mc: MFMailComposeViewController = MFMailComposeViewController()
mc.mailComposeDelegate = self
mc.setToRecipients(["\(mail)"])
But I get an error saying: "fatal error: unexpectedly found nil while unwrapping an Optional value"
PrepareForSegue, NSUserDefault and Singleton
You have a few possible options to pass your data to other views depending how you want that data to be handled, I will explain each for you and you can choose which one best fit your need.
prepareForSegue: Method
I recommend this method if you want to hold your data for 1 segue transition, it's a good cause to pass this again to another view afterward you need to create another prepareForSegue within the new view. here is an example on how to do this:
First, you create 2 variables in both views, 1 to send (currentViewController.swift) and 1 to receive (toViewyourGoingController.swift).
currentViewController.swift var dataToSend: AnyObject?
ViewYourGoingController.swift var dataToReceive: AnyObject?
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
//Check your segue, this way you can transfer different data to different view. also make sure the identifier match your segue.
if segue.identifier == "toViewYourGoing" {
//Initial your second view data control
let ExchangeViewData = segue.destinationViewController as! toViewyourGoingController
//Send your data with segue
ExchangeViewData.dataToReceive = dataToSend
}
}
NSUserDefault
Now this method is good if you want to keep your data live as long as the app is installed, once the app is removed this will reset automatically. You also have the option to update the value of the key if you wish, here is how you do NSUserDefault:
I always like to register my NSUserDeafult to default setting, a lot of people just continue with the second step without registering.
Register NSUserDefault in AppDelgate.swift
NSUserDefaults.standardUserDefaults().registerDefaults(["valueName": AnyObject])
Set Value to your NSUserDefault, this depends on what type of data you're storing, should match the one with your registration if you did register. (Example of Boolean data type below)
NSUserDefaults.standardUserDefaults().setBool(true, forKey: "valueName") //Bool Data Type
Available types:
Make sure you synchronize once you set the value to the NSUserDefault, this way it will update instantly, otherwise it will update when it get a chance.
NSUserDefaults.standardUserDefaults().synchronize()
Receive Value: this will receive boolean value since we set boolean and register boolean.
let Variable: Bool! = NSUserDefaults.standardUserDefaults().boolForKey("valueName")
Singleton
Now singleton is basically a global variable that you can use them in any views, but some developers experience some bugs and difficulties, use it at your own risk, I recommend this method when you're definite that you will use that data a lot (STILL RISKY), but this method is like goddess of data handling :).
Create a NSObject subclass and call it DataManager.swift (I call it data manager cause it handle data.) as following:
import UIKit
class DataManager: NSObject {
//Store Data Globally
static var someData: Boo! //This Boolean, you can choose whatever you want.
}
the static is what keep your data live.
Now you can store and receive someData from anywhere like you handle any data type like this.
//Store
DataManager.someData = true
//Receive
print(DataManager.someData)
Challenges:
You can also use
Keychain
Sergey Kargopolov will walk you through how to use a third party to use swift keychain. Otherwise, you can take even harder challenge and create one yourself :P .
Key-Value Data in iCloud
Use CoreData to save it in a database, then you can perform a fetch request to get it back out of the database.
Very simple look it up here:
https://www.youtube.com/watch?v=3IDfgATVqHw
This is all purely for educational purposes, to help me get a better understanding of how Parse as well as Swift operates.
I would like to make it so a user is only able to like an item once (not being able to hit a button multiple times), as currently, I'm utilizing an anonymous system with Parse.
Would I essentially use an if method with PFUser.CurrentUser() in the likeButton method to halt a user from hitting like again or would I use NSUserDefaults?
I'm not able to post code currently as I'm not near my laptop, however I could later if it helps. Still curious if I could get some info before that however.
Sample code I found on here from a previous question, which essentially implements the same idea.
#IBAction func likeButton(sender: AnyObject) {
let hitPoint = sender.convertPoint(CGPointZero, toView: self.tableView)
let hitIndex = self.tableView.indexPathForRowAtPoint(hitPoint)
let object = objectAtIndexPath(hitIndex)
object.incrementKey("count")
object.saveInBackground()
self.tableView.reloadData()
}
Would I call NSUsersDefaults to stunt the user from hitting it more than once?
Instead of calling saveInBackground(), you'd better call the method saveInBackgroundWithBlock: instead. So the strategy is very simple:
First of all, define a 'busy' flag for the object (For example: savingInBackground) and store it wherever you like ( If you are showing 1 item then simply declare a Bool property / If you are showing a list of Item then declare a Dictionary with format ["objectID/Index": Bool]). This flag should be set to true for the item being saved in the background.
Whenever use taps on a Like button
If current item's savingInBackground flag is true, then do nothing
Else:
Set item's savingInBackground to true
Increase Like count and Call saveInBackgroundWithBlock:
In the completion block of saveInBackgroundWithBlock:, set savingInBackground back to false.
I am on train now so I can't write example code, but I hope that it's clear enough to help you to achieve what you want.
I thought this would be simple, but I'm really struggling with it. I have a map view in a tab bar controller, and I have a viewController that when you tap a button, it is supposed to save the user's coordinates and put an annotation on the map. I thought I could just make a boolean newPost, and set it as true, and then in the viewDidLoad method for my map view, say,
if newPost {
var newAnnotation = MKPointAnnotation()
var newPostCoordinate = CLLocationCoordinate2DMake(userPosts.last!.postLatitude, userPosts.last!.postLongitude)
newAnnotation.coordinate = newPostCoordinate
newAnnotation.title = userPosts.last!.postTitle
mainMapView.addAnnotation(newAnnotati
newPost = false
}
Unfortunately, the mapView doesn't reload when I go back to it after going to the new post viewController, so the viewDidLoad method doesn't get called again.
So instead, I created a new method, and tried to call it when the post button on the new post viewController is tapped. This is where I got stuck. I thought it would just be:
mapViewController.theMethodIWantToRun()
but I end up with a "missing argument for parameter #1 in call" error. My method doesn't have any arguments or return anything, so I don't think I should need arguments...
I feel like this is a pretty dumb question, but if I could figure it out, I wouldn't be here.
If you think there's a better way to do what I'm trying to do, feel free to let me know! Thanks!
The easiest way to do that is to move your newPost condition in viewWillAppear method. Otherwise the best approach to send data between controllers is by using delegation pattern
I want to display a login view to my users if they are not logged in and the main view if they are.
In my header file I define a variable to hold the logged in status
#define loggedIn 0
I figure I should then reference this in the initWithNibName method and then decide which nib to load.
Is the right way of doing it?
If so can someone help me out with the exact code?
Thanks for any help
I don't think you understand how to use define directives.
All this line...
#define loggedIn 0
... does it cause the compiler to substitute a zero everywhere in the code that the text "loggedIn" appears.
So, if you have code that says:
if (loggedIn) {
//... load one nib
}else{
// .... load another nib
}
The compiler turns that into:
if (0) {
//... load one nib
}else{
// .... load another nib
}
In this case, zero will evalute to false and the second nib will always be loaded.
These types of defines are only used in this way in development so you can force the app into a specific state. For example, if you wanted to test the second nib repeatedly you would define "loggedIn" to zero and if you wanted to test the first you would define "loggedIN" as 1.
What you need to do is to do a test of some kind to see if the user is logged in. I don't know what that test would be as it varies on what your logging into. Then depending on the results of that test, you would load one nib or the other.
The define directive wouldn't have anything to do with it.
#define is not what you want, as explained by TechZen.
You should rather use an int or a BOOL to do this.
For example:
BOOL loggedIn = NO;
- (void) login {
// Check login details, if correct continue, if not, break.
BOOL loggedIn = YES
}
Then you could use that in another function;
if (loggedIn == YES) {
NSLog(#"Logged in!");
// Load nib
}