Monday, 24 September 2018

UITableViewCell Animation

Hello friends,
This article is use for UITableViewCell animation.
In most of the application for represent data you can use UITableView.
When UITableView represent at that time you need to animated UITableViewCell for best UI experience of application.

How to use
You need to implement UITableView method 

func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forRowAt indexPath: IndexPath) {
     
        ///Animation code
    
    }

Now you need to developed FadeIn animation like this

cell.alpha = 0
        UIView.animate(withDuration: 0.1, delay: (0.1 * Double(indexPath.row)),  animations: {
            cell.alpha = 1.0
        }, completion: nil)

For more animation see this video



For above animation I have created extension for UITableViewCell

extension UITableViewCell{
    
    /// Table view cell fade in animation for best way to represent
    /// tableview
    ///
    /// - Parameters:
    ///   - duration: animation duration default value 0.1
    ///   - index: cell index
    func fadeInAnimation(withDuration duration: Double = 0.1,forIndex index : Int) {
        self.alpha = 0
        UIView.animate(withDuration: duration, delay: (duration * Double(index)),  animations: {
            self.alpha = 1.0
        }, completion: nil)
    }
    
    /// Table view cell bounce animation for best way to represent
    /// tableview
    ///
    /// - Parameters:
    ///   - duration: animation duration default value 0.8
    ///   - delay: animation delay default value 0.05
    ///   - index: cell index
    func bouncingAnimation(withDuration duration: Double = 0.8,withDelay delay : Double = 0.05,forIndex index : Int) {
        self.transform = CGAffineTransform(translationX: 0, y: self.frame.height)
        UIView.animate(withDuration: duration,delay: delay * Double(index),usingSpringWithDamping: 0.8,initialSpringVelocity: 0.1,animations: {
            self.transform = CGAffineTransform(translationX: 0, y: 0)
        })
    }
    
    /// Table view cell move in animation for best way to represent
    /// tableview
    ///
    /// - Parameters:
    ///   - duration: animation duration default value 0.5
    ///   - delay: animation delay default value 0.08
    ///   - index: cell index
    func moveInAnimation(withDuration duration: Double = 0.5,withDelay delay : Double = 0.08,forIndex index : Int) {
        self.alpha = 0
        self.transform = CGAffineTransform(translationX: 0, y: self.frame.height / 2)
        UIView.animate(withDuration: duration,delay: delay * Double(index),animations: {
            self.alpha = 1
            self.transform = CGAffineTransform(translationX: 0, y: 0)
        })
    }
    
    /// Table view cell right side to in animation for best way to represent
    /// tableview
    ///
    /// - Parameters:
    ///   - duration: animation duration default value 0.5
    ///   - delay: animation delay default value 0.08
    ///   - index: cell index
    func rightInAnimation(withDuration duration: Double = 0.5,withDelay delay : Double = 0.08,forIndex index : Int) {
        self.transform = CGAffineTransform(translationX: self.bounds.width, y: 0)
        UIView.animate(withDuration: duration,delay: delay * Double(index),animations: {
            self.transform = CGAffineTransform(translationX: 0, y: 0)
        })
    }
    
    /// Table view cell left side to in animation for best way to represent
    /// tableview
    ///
    /// - Parameters:
    ///   - duration: animation duration default value 0.5
    ///   - delay: animation delay default value 0.08
    ///   - index: cell index
    func leftInAnimation(withDuration duration: Double = 0.5,withDelay delay : Double = 0.08,forIndex index : Int) {
        self.transform = CGAffineTransform(translationX: -self.bounds.width, y: 0)
        UIView.animate(withDuration: duration,delay: delay * Double(index),animations: {
            self.transform = CGAffineTransform(translationX: 0, y: 0)
        })
    }
}

And you can simply use like 

func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forRowAt indexPath: IndexPath) {
        if (animationType == .bounce){
            cell.bouncingAnimation(forIndex: indexPath.row)
        }else if (animationType == .moveIn){
            cell.moveInAnimation(forIndex: indexPath.row)
        }else if (animationType == .leftIn){
            cell.leftInAnimation(forIndex: indexPath.row)
        }else if (animationType == .rightIn){
            cell.rightInAnimation(forIndex: indexPath.row)
        }else if (animationType == .side){
            if (indexPath.row % 2 == 0){
                cell.leftInAnimation(forIndex: indexPath.row)
            }else{
                cell.rightInAnimation(forIndex: indexPath.row)
            }
        }else{
            cell.fadeInAnimation(forIndex: indexPath.row)
        }
    }

The sample code for illustrated in this post is available on GitHub

Thank you.

Wednesday, 19 September 2018

Optional Types

Optional represents either wrapped value or nil.
Optionals are generic enum type that works as wrapper.

Basically wrapper allow variable have 2 states:

  1. User define type
  2. nil (that represent no value)
In swift nil value must be optional.
Optional can be created by appending either "?" or "!".

example :

var name : String? = nil
var lname : String! = nil

"?" must be explicitly unwrapped where as "!" automatically unwrapped.
Conditionally unwrapped use "?" optional binding where as force unwrapped use "!" operator. If you force unwrapped variable and value is nil then program will throw exception and crash so be careful.

example :

var lname : String! = nil
print(lname!)

Output :

fatal error: unexpectedly found nil while unwrapping an Optional value

Safe unwrapping :

Using if-let statement safe unwrap

example :

func safeUnwrap(withName name : String?){
    if let userName = name{
        print(userName)
    }else{
        print("name value is nil")
    }
}

safeUnwrap(withName: "Pratik")

Output :

Pratik

safeUnwrap(withName: nil)


Output :

name value is nil

Using guard-let statement safe unwrap

example :

func safeUnwrap(withName name : String?){
    guard let userName = name else{
        print("user name not found")
        return
    }
    print(userName)
}

safeUnwrap(withName: "Pratik")

Output :

Pratik

safeUnwrap(withName: nil)


Output :

user name not found

Using Coalescing operator safe unwrap

example :

var name : String? = nil
print(name ?? "name value is nil")


Output :

name value is nil

var name : String? = nil
name = "Pratik"
print(name ?? "name value is nil")


Output :

Pratik

You can also use Optional chaining in order to call method,property or subscript.

example : 

struct Family{
    func printName() {
        print("Hello friends")
    }
}

var objFamily : Family?
objFamily?.printName()

Output :

no print 

var objFamily : Family? = Family()
objFamily?.printName()

Output :

Hello friends



unwrapped using optional type in swift
Optional types unwrapped