Using unicode markers  (LTR: 0x200E, RTL:200F) to align “hybrid RTL/LTR strings” correctly.
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So you have some text that contains both Arabic and English languages at the same time? and having difficulty aligning it because sometimes it starts with english, and other times it starts with Arabic?

The following example illustrates
– this problem 🐛
– some hacky way to solve it 👺
– and the correct way to solve it 🧐.

3 example labels

Top line: shows a line that is being rendered incorrectly, because the first word is Arabic, and you are expecting it to show up on the left, but it’s not 🤦🏻.

Middle line: one hacky way to solve this, is to start your text all the time with a LTR word, not the best solution 👺

Bottom line: this is showing up correctly, because it’s adjusted using unicode markers.

Unicode characters set offers two marker characters (LTR: 0x200E, RTL:200F). These are invisible, but control the direction, I just need to add this \u{200E} to force the wrapping direction.

Playground example:

import UIKit
import PlaygroundSupport

extension String {

    func withHighlighted(word: String) -> NSMutableAttributedString {
        let attributes = [
            [NSAttributedString.Key.foregroundColor:UIColor.blue],
            [NSAttributedString.Key.font: UIFont.boldSystemFont(ofSize: 14)]
        ]
        
        let range = (self as NSString).range(of: word)
        let result = NSMutableAttributedString(string: self)
        for attribute in attributes {
            result.addAttributes(attribute, range: range)
        }
        return result
    }
    
}

class MyViewController : UIViewController {
    
    override func loadView() {
        
        let view = UIView()
        let topLabel = UILabel()
        let middleLabel = UILabel()
        let bottomLabel = UILabel()

        topLabel.frame = CGRect(x: 40, y: 40, width: 300, height: 20)
        middleLabel.frame = CGRect(x: 40, y: 80, width: 300, height: 20)
        bottomLabel.frame = CGRect(x: 40, y: 120, width: 300, height: 20)
        
        let word1 = "عبد الله"
        let word2 = "added a new comment"
        let adjustor = "\u{200E}"
        
        topLabel.attributedText = "\(word1) \(word2)".withHighlighted(word: word1)
        middleLabel.attributedText = "note: \(word1) \(word2)".withHighlighted(word: word1)
        bottomLabel.attributedText = "\(adjustor) \(word1) \(word2)".withHighlighted(word: word1)
        
        view.addSubview(topLabel)
        view.addSubview(middleLabel)
        view.addSubview(bottomLabel)

        self.view = view
        
    }
    
}

PlaygroundPage.current.liveView = MyViewController()

Swift Bitwise Operators (with a couple of practical examples)
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Bitwise operators are rarely used in everyday swift programming
⚠️ : not to be confused by Logical Operators like “&&” and “||”

It’s mainly used to perform operations on individual bits,  they are extremely useful and used in FlagsGraphicsNetworkingEncryption

OperatorDescription
Binary AND
|    Binary OR
^   Binary XOR
~    Binary One’s Complement
<<   Binary Shift Left
>>    Binary Shift Right
Swift Bitwise Operators



First, a refresher on the truth table of XOR, it gives True if both A and B are Different

ABResult
TRUETRUEFALSE
TRUEFALSETRUE
FALSETRUETRUE
FALSEFALSEFALSE
XOR Truth Table


The basic code to represent integers as bits, and each operator and it’s result … 🧐

extension Int {
    
    var binaryDescription: String {
        var binaryString = ""
        var internalNumber = self
        for _ in (1...self.bitWidth) {
            binaryString.insert(contentsOf: "\(internalNumber & 1)", at: binaryString.startIndex)
            internalNumber >>= 1
        }
        return "0b " + binaryString
    }
    
}

func bitwise_example() {
    
    let x1 = 0x1
    let x2 = 0x2

    print("x1\t", x1.binaryDescription )
    print("x2\t", x2.binaryDescription )
    
    let binary_and = (x1 & x2)
    let binary_or = (x1 | x2)
    let binary_xor = (x1 ^ x2)
    let binary_complement = (~x1)
    let binary_shiftL = (x1 << 1)
    let binary_shiftR = (x1 >> 1)

    print("&\t",  binary_and.binaryDescription )
    print("|\t", binary_or.binaryDescription )
    
    print("^\t", binary_xor.binaryDescription )
    print("~\t", binary_complement.binaryDescription )
    print("<<\t", binary_shiftL.binaryDescription )
    print(">>\t", binary_shiftR.binaryDescription )
    
}

Output

x1	 0b 0000000000000000000000000000000000000000000000000000000000000001
x2	 0b 0000000000000000000000000000000000000000000000000000000000000010
&	 0b 0000000000000000000000000000000000000000000000000000000000000000
|	 0b 0000000000000000000000000000000000000000000000000000000000000011
^	 0b 0000000000000000000000000000000000000000000000000000000000000011
~	 0b 1111111111111111111111111111111111111111111111111111111111111110
<<	 0b 0000000000000000000000000000000000000000000000000000000000000010
>>	 0b 0000000000000000000000000000000000000000000000000000000000000000

Real Life Usage for them:

1- Color Format Conversion
Most probably, you would have such an extension in your boilerplate iOS app, it converts HEX colors into UIColor.

extension UIColor {
   convenience init(red: Int, green: Int, blue: Int) {
       assert(red >= 0 && red <= 255, "Invalid red component")
       assert(green >= 0 && green <= 255, "Invalid green component")
       assert(blue >= 0 && blue <= 255, "Invalid blue component")

       self.init(red: CGFloat(red) / 255.0, green: CGFloat(green) / 255.0, blue: CGFloat(blue) / 255.0, alpha: 1.0)
   }

   convenience init(rgb: Int) {
       self.init(
           red: (rgb >> 16) & 0xFF,
           green: (rgb >> 8) & 0xFF,
           blue: rgb & 0xFF
       )
   }
}

2- Quick & Dirty hashing

let a = 4012
let b = 8102
let c = 9101

func dirtyHash(a: Int, b: Int, c: Int) -> Int{
    return ( a ^ b ^ c ^ 9999)
}

3- Base64 Encoding

Base64 encoding converts a series of 8 bit bytes into 6 bit character lookup indexes. (SHIFT)ing, (AND)ing, (OR)ing, (NOT)ing are used for implementing the bit operations necessary for Base64 encode/decode.

4- Checking if a number is Odd/Even.

func isEven(number: Int) -> Bool{
    return ((number & 0x1) == 0)
}

func isOdd(number: Int) -> Bool{
    return ((number & 0x1) > 0)
}

5- Solving Problems efficiently and in a performant way.
Write a program to swap the value of two variable.

Using temporary variable

c =  a; a = b; b = c; 

Without using temporary variable

a = a+b; b = a-b; a = a-b; 

Using bitwise operator

a = a^b; b = a^b; a = a^b; 

6- Calculating valid network addresses for a subnet

7- Calculating Permission in Role-based access control systems, RBAC.

8- Calculating Inverse Square Root very fastly
http://h14s.p5r.org/2012/09/0x5f3759df.html

Also:

Some people use bitwise operators to handle multiple error code together, each bit can hold a separate value.

N-bitmap can be a really cool and compact data structure.

Easily Tiling Images in interface builder, without code !
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images, with and without tiling

Tiling images in interface builder directly without code is easy…

1- add an image into assets catalogue.
2- select the asset, go to “editor” menu, then choose “Show Slicing”.
3- the asset image will show up as darker, with a button labeled “Start Slicing”, and you will be able to select the slicing type.


4- select how you want the image tiled, in normal cases you will have the setup like this, zeroed Left, Right, Top and Bottom, and the Width & Height as the image dimensions.


5- for tilability, the image content mode should be fill, not fit.

Keep experimenting, and go wild with your Imagination, sample of playing with small tilable images I have..