Swift - Notify ViewController from AppDelegate On FCM / APN

Hello,

Recently I tried  my hands on iOS app after long time as I had to convert one of our hybrid app to native app on urgent basis. There I had webview where I was loading my html app. On FCM message receieved we need to send URL received in FCM to webview and load the URL.

So here in this blog I will mention the procedure for it.

First of all in AppDelegate we have didReceiveRemoteNotification method. There we will create notification for it. Here is the code.

let url = dict

serverURL = url;

let notificationName = Notification.Name("updateWebView")

NotificationCenter.default.post(name: notificationName, object: nil)

Now in the ViewController where you want to make updates, subscribe to this notification in viewDidLoad function.

override func viewDidLoad() {

  let notificationName = Notification.Name("updateWebView")

  NotificationCenter.default.addObserver(self, selector:            #selector(ViewController.updateWebView), name: notificationName, object: nil)

}

And then add function in ViewController.

@objc func updateWebView() {

  let appDelegate = UIApplication.shared.delegate as! AppDelegate

  let serverURL = appDelegate.serverURL

        

  guard let url = URL(string: serverURL!) else {

     print("Invalid URL")

     return

  }

        

  let request = URLRequest(url: url)

  webView.load(request)

}

That's it and now you will have data passed from AppDelegate to ViewController. This method you can pass any kind of data from FCM to respective ViewController.

Hope this helps you.

Cocoa OSX NSTextField Allow Only Integer Value

Hello,

Recently I was working on MAC OSX application where we have a view with some textfields. Where in few textfields where only numeric values are allowed. In this blog I will explain how to do this.

I used NSNumberFormatter for that. First you have to create a class which extends NSNumberFormatter.

Go to your .m file and add new interface.

@interface OnlyIntegerValueFormatter : NSNumberFormatter

@end

Now implement this interface in same file.

@implementation OnlyIntegerValueFormatter

- (BOOL)isPartialStringValid:(NSString*)partialString newEditingString:(NSString**)newString errorDescription:(NSString**)error

{

    if([partialString length] == 0) {

        return YES;

    }

    

    NSScanner* scanner = [NSScanner scannerWithString:partialString];

    

    if(!([scanner scanInt:0] && [scanner isAtEnd])) {

        NSBeep();

        return NO;

    }

    

    return YES;

}

@end

That's it. Now create instance of OnlyIntegerValueFormatter and assign it to NSTextField. 

OnlyIntegerValueFormatter *formatter = [[OnlyIntegerValueFormatter alloc] init];

[self.onlyIntegerTextField setFormatter:formatter];

That's it. Now if you try to type characters in the textfield, it won't allow it. 

Introduction to Swift - the latest programming language from Apple

So Apple stunned all the developers around the globe by introducing new language instead of new iPhones, iPhones or iWatches. Let's see what exactly is the Swift.

Apple says the following about the release of Swift:

"Swift is a powerful new programming language for iOS and OS X® that makes it easier than ever for developers to create incredible apps. Designed for Cocoa® and Cocoa Touch®, Swift combines the performance and efficiency of compiled languages with the simplicity and interactivity of popular scripting languages. By design, Swift helps developers write safer and more reliable code by eliminating entire categories of common programming errors, and coexists with Objective-C® code, so developers can easily integrate Swift into their existing apps. Xcode® Playgrounds make writing Swift code incredibly interactive by instantly displaying the output of Swift code."

Swift code can live right besides C and Objective-C code in the same app. The syntax is quite similar to JavaScript. Here are some of the features of it.

• Closures (similar to blocks in C and Objective-C) unified with function pointers
• Tuples and multiple return values
• Generics
• Fast and concise iteration over a range or collection
• Structs that support methods, extensions, protocols.
• Functional programming patterns, e.g.: map and filter

Here is the first lesson of Swift. How to define a variable and a constant. Constants and variables must be defined before they are used. You can define constants with let keyword and variable with var keyword. For example

let maximumLoginAttemptsAllowed = 10
var currentLoginAttempt = 0

So here is a constant maximumLoginAttemptsAllowed which has a value 10 and a variable currentLoginAttempt which has value 0.