Run an Xcode project on an iOS device without US$99 Apple Developer account (Configuration for iPhone)

Since iOS 9, it is possible to install the app of an Xcode project to an iOS device without paying for a US$99 Apple Developer account. The steps to download the app to an iPhone/iPad are demonstrated with an iOS 10 device as below:

When press the build and run button of Xcode:

You may see a Could not launch "deviceName" dialog like this:

So follow the instruction on the Xcode dialog to select General -> Profiles & Device Management on the iOS device (iPhone/iPad).

Select the device.

Select "Trust (Apple ID)".

 Select "Trust".

Then the app should run on the iPhone / iPad.

For more information about Xcode configuration, see this:

How to run an Xcode project on an iOS device without payment for the US$99 Apple Developer account (2021) (StudySwift)

Visualized custom color in swift code with Color Literal

This post is written with Xcode 8.3.3 and Swift 3.1.

It is very common to set a UIColor with autocomplete as below:

However, there is a better way to select a custom color visually.
Type Co to find Color Literal with Xcode' automatic complete feature.

Then select a color. There are more color options with the color literal than with UIColor.colorName.

So we can see the color in the code instead of strings such as orange, red, ... ect.

There are also literal icons/images. For more information, see:

Be Literal! – iOS App Development

Mac Technique: Show the desktop with F11 key

To show the desktop with Mac, simply press [fn] + [F11] on a Mac's keyboard or press [F11] on an external USB keyboard.

How to Sort Array, Dictionary, and Array of Tuples

The code below shows how to sort an array, a dictionary or an array of tuples in Swift 3.1 with Xcode 8.3.1 Playground. Sorting can be done in ascending or descending order. A dictionary can be sorted by key or by value.

Note: When sorting a dictionary, the returned type is an array of tuples.

//Array
let array = [3, 5, 9, 7, 4, 1, 2]

let arrayInc = array.sorted()
let arrayDec = array.sorted(by: >)

//Dictionary
let dict = ["A": 123, "B": 789, "C": 567, "D": 432]

print(dict)

let dictKeyInc = dict.sorted(by: <)
let dictKeyDec = dict.sorted(by: >)

print(dictKeyInc)
print(dictKeyDec)

let dictValInc = dict.sorted(by: { $0.value < $1.value })
let dictValDec = dict.sorted(by: { $0.value > $1.value })

print(dictValInc)
print(dictValDec)

for item in dictValDec {
    print("key:\(item.key) value:\(item.value)")
}

//Array of Tuples
let tupleArray = [("A", 123), ("B", 789), ("C", 567), ("D", 432)]

let tupleArrayInc = tupleArray.sorted(by: { $0.1 < $1.1 })


print(tupleArrayInc)

Result:

["B": 789, "A": 123, "C": 567, "D": 432]
[(key: "A", value: 123), (key: "B", value: 789), (key: "C", value: 567), (key: "D", value: 432)]
[(key: "D", value: 432), (key: "C", value: 567), (key: "B", value: 789), (key: "A", value: 123)]
[(key: "A", value: 123), (key: "D", value: 432), (key: "C", value: 567), (key: "B", value: 789)]
[(key: "B", value: 789), (key: "C", value: 567), (key: "D", value: 432), (key: "A", value: 123)]
key:B value:789
key:C value:567
key:D value:432
key:A value:123
[("A", 123), ("D", 432), ("C", 567), ("B", 789)]

Reference

Sort Dictionary by Key Value
cannot assign value of type '[(string, string)]' to type '[string : string]'

Dictionary of Arrays in Swift 3

The code below shows how to include an array in a dictionary in Swift 3.1 with Xcode 8.3.1 Playground.

dictionarySemitones["abc"]=[1,2,3]
dictionarySemitones["def"]=[4,5,6]

print(dictionarySemitones)
print(dictionarySemitones["abc"]!)

Reference:

A Dictionary of Arrays in Swift

Convert an Integer Array to a String

The code below shows how to convert an integer array to a string in Swift 3.1 with Xcode 8.3.1 Playground.

let arrayInt = [1, 2, 3, 4, 5]
let string = "\(arrayInt)"
print(string)

Reference:

How can I convert an Int array into a String? array in Swift

Conversion from Numbered Musical Notation to Musical Note Letters

The code below converts Numbered Musical Notation (簡譜) to musical note letters using Xcode 8.3.2 playground in Swift 3.1. Techniques used in the code involves:

1. Separating a string into an array
2. Type casting each array element into an integer
3. Converting the numerical notation into a matched letter
4. Joining all letters into a single string

//Twinkle, Twinkle, Little Star 一閃一閃亮晶晶
let numberedNotation = "1 1 5 5 6 6 5"

//1. Separating a string into an array let numberedNoteArray = numberedNotation.components(separatedBy: " ")

let lookupTable = ["C","D","E","F","G","A","B"]

var noteArray = [String]()

for note in numberedNoteArray {
    //2. Type casting each array element into an integer
    let noteInt = Int(note)!

    //3. Converting the numerical notation into a matched letter
    let noteChar = lookupTable[noteInt-1]
    noteArray.append(noteChar)
}

//4. Joining all letters into a single string let noteString = noteArray.joined(separator: " ")

print("\(noteString)")

Result:

C C G G A A G