Swift Tutorial - Part 1 - Hello World App

Introduction to Swift

Video Description 

Before starting Swift tutorial we should know that some tutorials that I have created for Objective-C language are valid for swift, like the first three ones that we will introduce here.

Download Xcode

Here is the link for both video and description of how we can download the Xcode ( iOS development environment)

http://huxtek.blogspot.com/2013/12/fist-post.html

Create Hello World App

Creating Hello World App in Swift is almost identical with Objective-C one. It has just one small difference which is choosing the language of programming. Instead of Objective-C, you should choose Swift.

http://huxtek.blogspot.com/2013/12/creating-hello-world-app-for-iphone-ipad.html

Xcode components

In this tutorial I have explained each components of Xcode and even after 2 versions of iOS (8 and 9) we have similar layout for Xcode menus and button. They just changed the icons. So in order to get familiar with these components please watch this tutorial.

http://huxtek.blogspot.com/2013/12/description-of-xcode-components.html

iOS Tutorial - Part 35 - Popover for iPhone and iPad

Create Popover for iPhone and iPad

Video Description 

Sometimes we don't want to cover the whole view for showing another view controller. This is mostly for iPad because it has larger screen. But it's also possible to show popover on iPhone. Creating a popover is very easy, it's a type of connection between view controllers. All you have to do is to connect the button or whatever action you want to another view controller by control dragging and the choose "Present As Popover", that's it. This will show popover only for iPad but for iPhone you have to do one more step.

Popover for iPhone

iOS 8 offered an easy way to implement popover for iPhone. All you have to do is to declare UIPopoverPresentationControllerDelegate:

@interface ViewController () <UIPopoverPresentationControllerDelegate>

Then put the view controller delegate equal to self:

self.popoverTvc.popoverPresentationController.delegate = self;

And at the end implement the delegate method:

- (UIModalPresentationStyle)adaptivePresentationStyleForPresentationController:(UIPresentationController *)controller
{
    return UIModalPresentationNone;
}

Adapt the popover size based on the content

The popover that we created so far has not a proper size. The default size is very big and unnecessary. In order to fix this issue we need to override the prefferedContentSize property of the popover view controller. In this example we have a table view and we need to get the size of the table view and show only the cells that has value (not empty cells).

if (self.tableView && self.presentingViewController) {
        self.preferredContentSize = [self.tableView sizeThatFits:self.presentingViewController.view.bounds.size];
    }

First we chech if tableView and presentingViewController (The view controller that is presenting at that moment) is not nill. then we set the preferredContentSize equal the tableiew size that fits presentingViewController size.

Download

Download this app here

iOS Tutorial - Part 34 - Split View Controller, iPad apps

Create an iPad app

Video Description 

In order to create an iPad app, all we have to do is to select iPad from the dropdown menu during the process of creating the application. It's also possible to make the existing app working on the iPad as well but this would be the subject of the future tutorial. For now we select iPad instead of iPhone when we want to create a new project.

Split View Controller

In order to create a master details view we need to use Split View Controller. If we start a new project by selecting Single View application, we can drag Split View Controller from Object library into Xcode interface. But in this tutorial we use the easiest way and instead of using single view app, we select Master-Detail Application so it adds some default classes and views for us. In Master part we have a tableView and we connect the cell via control+drag to the details view and from the opening popup for type of connection, we select the "Show Detail".

Download

Download this App from HERE.

iOS Tutorial - Part 33 - Core Data II

Core Data II

Video Description 
In previous session we learnt how to add items inside of database, in this tutorial we will learn how to search through the database and also the proper way of adding items inside of database.

Proper way of adding items in database

Previous tutorial showed the easiest way of adding items inside of database but here is the best practice of adding data into database:

+ (Students *)addStudentInfoFromDictionary:(NSDictionary *)studentInfo
{
    AppDelegate *appDelegate= (AppDelegate *)[[UIApplication sharedApplication] delegate];
    NSManagedObjectContext *context = [appDelegate managedObjectContext];
    
    Students *studentEntity = nil;
    
    NSString *studentId = studentInfo[@"studentId"];
    NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"Students"];
    request.predicate = [NSPredicate predicateWithFormat:@"studentId = %@", studentId];
    
    NSError *error;
    NSArray *matches = [context executeFetchRequest:request error:&error];
    
    
    if (!matches || error || ([matches count] > 1))
    {
        //Handle Errors
    }
    else if ([matches count])
    {
        //Returns the existing object
        studentEntity = [matches firstObject];
    }
    else
    {
        //Create a new Object
        studentEntity = [NSEntityDescription insertNewObjectForEntityForName:@"Students" inManagedObjectContext:context];
        studentEntity.studentId = [studentInfo valueForKey:@"studentId"];
        studentEntity.name  = [studentInfo valueForKey:@"name"];
        studentEntity.lastName = [studentInfo valueForKey:@"lastName"];
        
        NSError *error;
        if (![context save:&error]) {
            NSLog(@"Whoops, couldn't save: %@", [error localizedDescription]);
        }
    }
    return studentEntity;
}

First we check for a unique identifier in order to avoid duplicating data. In this example studentId is our unique identifier. We request a fetch through the database via NSFetchRequest. It needs the entity name in order to be initialized. Our entity name is "Students" so we add Students as entity name. Then we define a predicate. Predicate is for defining our query for search. The following line means, give me all the data that has studentId that is equal to the one that is passed to this function.

[NSPredicate predicateWithFormat:@"studentId = %@", studentId];

Since during fetch request we may get some errors, we define NSError. Then we execute the fetch request and assign the result to an array because it returns all matched results as an array. Now we have to check the matches. If matches null or it's more than one item or error is not null, we know that we have error and this if statement is for handling errors. matches should not be more than one because studentId is unique and we should have only one instance of that ID.
If matches not null and equals one, it goes to the second statement. If it goes to this statement it shows that we had this item already in the database so we just return the mach that we found.
If non of the above statements get valid, we know that it's totally new item and we add it to the database. The implementations is exactly like the one that we had in previous session.

Query the database (Search through Core Data)

Suppose that we want to search the database to find all the matches for a specific name or specific lastname. The following method can search the database to find all matches for the name and lastname that you specify. It uses the same NSFetchRequest format that we used above. Also the same NSPredicate but with different format. This time we want to check for name, so it searches for name. If we want to search the name and lastname, we put AND in our format. There are other things that we can use in our format like OR. Based on your needs you can find the proper format and pass it into the predicateWithFormat. The second function is a helper function to create a temporary dictionary for each result.

+ (NSArray *)searchStudensByName:(NSString *)name lastname:(NSString *)lastname
{
    AppDelegate *appDelegate= (AppDelegate *)[[UIApplication sharedApplication] delegate];
    NSManagedObjectContext *context = [appDelegate managedObjectContext];
    
    NSError *error;
    NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"Students"];
    request.predicate = [NSPredicate predicateWithFormat:@"name == %@ AND lastName == %@", name, lastname];
    
    NSArray *fetchedObject = [context executeFetchRequest:request error:&error];
    NSMutableArray *results = [[NSMutableArray alloc] init];
    
    for (Students *studentEntity in fetchedObject)
    {
        [results addObject:[self createObjectFromEntity:studentEntity]];
    }
    return results;
}

+(NSDictionary *)createObjectFromEntity:(Students *)studentInfo
{
    NSMutableDictionary *tempDict = [[NSMutableDictionary alloc] init];
    tempDict[@"name"] = studentInfo.name;
    tempDict[@"lastName"] = studentInfo.lastName;
    tempDict[@"studentId"] = studentInfo.studentId;
    return tempDict;
}

Download

Download this App from HERE.

iOS Tutorial - Part 32 - Core Data I

Core Data I

Video Description 
In iOS we have two options for adding data into database. First option is Core Data and second option is SQLite. Since Core Data is more powerful and could be used in more object oriented way, so we will only talk about the first option, which is Core Data.

Add Entity, Add Attributes

If you check mark core data when you create the application, you would see a file with suffix "xcdatamodeld". If you click on it you would see
 
You can press plus button at the bottom of the page to add a new entity. Then you can add attributes by pressing add button under the attributes section. Each attribute needs a type. Here in the above screenshot all attributes are type string. Once we add all of the entities and attributes we want, we should create NSManagedObject subclass in order to have more object oriented programming style. To create NSManagedObject subclass, click on the file with suffix "xcdatamodeld" on your project structure and the from the tool menu, select Editor/Create NSManagedObject Subclass... .
Presee Next and then select the entity you want to create the subclass and then hit Create button to create your NSManagedObject class. If you open the created files you would see all of the attributes that you added for that entity. we can go ahead and add our a method in .m file for adding objects into database but it's not the best practice.

Category Files

Because later on the we may add more attribute into the application and if we auto generate the NSManagedObject superclass we would lose our functions, so it's better to add a Category class for this subclass. In order to create a category file, choose File / New / File ... Then select Objective-C File.
In the next screen give your file a name, and select a File Type as Category and select your entity name for the class field. Finally hit Create to create the Category file.

Add objects into database

Now we can add our method for adding objects into database. Here is the method we can create for adding objects:

+ (Students *)addStudentInfoFromDictionary:(NSDictionary *)studentInfo
{
    AppDelegate *appDelegate= (AppDelegate *)[[UIApplication sharedApplication] delegate];
    NSManagedObjectContext *context = [appDelegate managedObjectContext];
    
    Students *studentEntity = nil;
    
    //Create a new Object
    studentEntity = [NSEntityDescription insertNewObjectForEntityForName:@"Students" inManagedObjectContext:context];
    studentEntity.studentId = [studentInfo valueForKey:@"studentId"];
    studentEntity.name  = [studentInfo valueForKey:@"name"];
    studentEntity.lastName = [studentInfo valueForKey:@"lastName"];
    
    return studentEntity;
}

First two lines gets the context. Before using these two lines make sure you #import "AppDelegate.h" file. Next we create the instance of Students entity. We initialize it with the method insertNewObjectForEntityForName. Finally we can use entity properties to add our object value. Since we have this class in .m file we need to declare it in .h file so other classes can use it. So we should add the following line in the header file:

+ (Students *)addStudentInfoFromDictionary:(NSDictionary *)studentInfo;

Now we can use this method in any class we want. In this project we use it in our ViewController like bellow:

- (IBAction)addToDatabase:(UIButton *)sender
{
    NSDictionary *studentInfo = @{@"name": self.nameField.text,
                                  @"lastName": self.lastnameField.text,
                                  @"studentId": self.studentIdField.text};
    
    [Students addStudentInfoFromDictionary:studentInfo];
} 

Basically we create a dictionary with all the items we want to add into the database and then we pass it to the function that we creates in Student+Add class.

description property

Most Objective-C classes have a property called description. When you use this property it tries to get the description of that object. It's like toString method in other programming languages. We can use this property to get some output on the screen when we add an object into database. So we change the last line into the following line:

self.outPutTextView.text = [Students addStudentInfoFromDictionary:studentInfo].description; 

Download

Download this App from HERE.

iOS Tutorial - Part 31 - NSNotificationCenter (Broadcasting an event)

NSNotificationCenter

Video Description 

In order to broadcast an event through the entire application, we can use NSNotificationCenter API. The usage is very simple, here are the steps: 1- Add (Register) the notification

[[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(dismissAddVC)
                                                 name:@"CallDismissAddVC"
                                               object:nil];

2- Write the method that we want to be called

- (void)dismissAddVC
{
    //implementation of the method
}

3- Post (Broadcast) notification

[[NSNotificationCenter defaultCenter] postNotificationName:@"CallDismissAddVC" object:nil];

4- Remove the observer

[[NSNotificationCenter defaultCenter] removeObserver:self name:@"CallDismissAddVC" object:nil];

You should be careful not misuse NSNotificationCenter. For simple things like the app we created in this demo we better use delegate method, but for more complicated apps that you want to broadcast an event for more than 2 places, it's reasonable to use NSNotificationCenter.

Download

Download this App from HERE.

iOS Tutorial - Part 30 - NSUserDefaults, UISwitch

NSUserDefaults, UISwitch

Video Description 

NSUserDefaults

Sometimes we want to save some small amount of data, which is mostly user preferences. For example if they choose to save their username, we should be able to save the username even if they kill the app. There is a useful API for doing this, which is NSUserDefaults. It can save some specific types. The types that NSUserDefaults can save are as follow: 1-NSString 2-NSArray 3-NSDictionary 4-NSData 5-NSDate 6-NSNumber.

Store preferences (User defaults)

If we want to save a username like HuxTek we can do it like bellow. We set a "HuxTek" value for a key "username". So whenever we want to retrieve the "HuxTek" we should call a key "username".

    [[NSUserDefaults standardUserDefaults] setValue:@"HuxTek" forKey:@"username"]

Now if we want to retrieve the username we can do something like bellow:

    [[NSUserDefaults standardUserDefaults] stringForKey:@"username"];

If we want to store a boolean value we can use the following api:

    [[NSUserDefaults standardUserDefaults] setBool:NO forKey:@"switchState"];

and for retrieve this boolean value we should have:

    [[NSUserDefaults standardUserDefaults] boolForKey:@"switchState"]

UISwitch

UiSwitch is a simple class with simple API. The most important APIs are as follow

isOn

If we want to check if the switch value is on or off, we can use this property like bellow:

if (self.mySwitch.isOn)
{
    //Do something when switch value is true (ON)
}
else
{
    //Do something when switch value is false (OFF)
}

setOn

In order to set the value of the switch programmatically we can use setOn api.

[self.rememberMeSwitch setOn:YES];

Download

Download this App from HERE.