I have an sequence of ASCII codes in string format like (7297112112121326610511411610410097121). How to convert this into text format.
I tried below code :
func convertAscii(asciiStr: String) {
var asciiString = ""
for asciiChar in asciiStr {
if let number = UInt8(asciiChar, radix: 2) { // Cannot invoke initializer for type 'UInt8' with an argument list of type '(Character, radix: Int)'
print(number)
let character = String(describing: UnicodeScalar(number))
asciiString.append(character)
}
}
}
convertAscii(asciiStr: "7297112112121326610511411610410097121")
But getting error in if let number line.
As already mentioned decimal ASCII values are in range of 0-255 and can be more than 2 digits
Based on Sulthan's answer and assuming there are no characters < 32 (0x20) and > 199 (0xc7) in the text this approach checks the first character of the cropped string. If it's "1" the character is represented by 3 digits otherwise 2.
func convertAscii(asciiStr: String) {
var source = asciiStr
var result = ""
while source.count >= 2 {
let digitsPerCharacter = source.hasPrefix("1") ? 3 : 2
let charBytes = source.prefix(digitsPerCharacter)
source = String(source.dropFirst(digitsPerCharacter))
let number = Int(charBytes)!
let character = UnicodeScalar(number)!
result += String(character)
}
print(result) // "Happy Birthday"
}
convertAscii(asciiStr: "7297112112121326610511411610410097121")
If we consider the string to be composed of characters where every character is represented by 2 decimal letters, then something like this would work (this is just an example, not optimal).
func convertAscii(asciiStr: String) {
var source = asciiStr
var characters: [String] = []
let digitsPerCharacter = 2
while source.count >= digitsPerCharacter {
let charBytes = source.prefix(digitsPerCharacter)
source = String(source.dropFirst(digitsPerCharacter))
let number = Int(charBytes, radix: 10)!
let character = UnicodeScalar(number)!
characters.append(String(character))
}
let result: String = characters.joined()
print(result)
}
convertAscii(asciiStr: "7297112112121326610511411610410097121")
However, the format itself is ambigious because ASCII characters can take from 1 to 3 decimal digits, therefore to parse correctly, you need all characters to have the same length (e.g. 1 should be 001).
Note that I am taking always the same number of letters, then convert them to a number and then create a character the number.
Related
Objective-C code:
NSString *str = #"hi";
NSString *strDigit = #"1934"; (or #"193" may be a 3 digit or 4 digit value)
[dayText appendFormat:#"%#%4s,str,[strDigit UTF8String]];
The Objective-C code handles the output string with current alignment when it appears with 3 or 4 digits as output. It is correctly aligning to left and doesn't matter how much digits it is. Any one know how to handle this in Swift?
In Swift I tried with below code and the string is not adjusting the alignment according to the number of digits.
textForTrip += "\(str) \(String(format:"%4s", (strDigit.utf8))"
The %s format expects a pointer to a (NULL-terminated) C string
as argument, that can be obtained with the withCString method.
This would produce the same output as your Objective-C code:
let str = "Hi"
let strDigit = "193"
let text = strDigit.withCString {
String(format: "%#%4s", str, $0)
}
print(text)
It becomes easier if you store the number as integer instead of a
string:
let str = "Hi"
let number = 934
let text = String(format: "%#%4d", str, number)
print(text)
Try this below approach, that might help you
let strDigit = "\("1934".utf8)" //(or #"193" may be a 3 digit or 4 digit value)
var dayText = "Hello, good morning."
dayText += "\(strDigit.prefix(3))"
There is better way to convert from unichar to Character?
tried :
var unichar = ...
let str = NSString(characters: &unichar, length: 1) as String
let character = Array(str.characters)[0])
You can convert unichar -> UnicodeScalar -> Character:
let c = unichar(8364)
if let uc = UnicodeScalar(c) {
let char = Character(uc)
print(char) // €
} else {
print("illegal input")
}
Input values in the range 0xD800...0xDFFF
(high and low surrogates) are not allowed because they do not
correspond to valid Unicode scalar values.
If it is guaranteed that those input values do not occur then you
can simplify the conversion to
let char = Character(UnicodeScalar(c)!)
To replace a possible invalid input value by a default character
(e.g. a question mark), use
let char = Character(UnicodeScalar(c) ?? "?")
public class func stringForIcon(_ icon: NSInteger) -> Character {
return Character(UnicodeScalar(icon)!)
}
Lets say there is a string "johngoestoschool" it should become "JoHnGoEsToScHoOl" and incase if there is a special character in between it should ignore it for example given string "jo$%##hn^goe!st#os&choo)l" answer should be "Jo$%##Hn^GoE!sT#oS&cHoO)l"
From this answer, we in order to iterate we can do:
let s = "alpha"
for i in s.characters.indices[s.startIndex..<s.endIndex]
{
print(s[i])
}
Why can't we print the value of "i" here?
When we do i.customPlaygroundQuickLook it types int 0 to int4.
So my idea is to
if (i.customPlaygroundQuickLook == 3) {
s.characters.currentindex = capitalized
}
Kindly help
This should solve your function, the hard part is just checking weather the character is letters or not, using inout and replace range would give better performance:
func altCaptalized(string: String) -> String {
var stringAr = string.characters.map({ String($0) }) // Convert string to characters array and mapped it to become array of single letter strings
var numOfLetters = 0
// Convert string to array of unicode scalar character to compare in CharacterSet
for (i,uni) in string.unicodeScalars.enumerated() {
//Check if the scalar character is in letter character set
if CharacterSet.letters.contains(uni) {
if numOfLetters % 2 == 0 {
stringAr[i] = stringAr[i].uppercased() //Replace lowercased letter with uppercased
}
numOfLetters += 1
}
}
return stringAr.joined() //Combine all the single letter strings in the array into one string
}
Basically, I have a Float, for example: 3.511054256.
How can I extract n number of digits after the decimal point?
i.e. I'd like to retrieve 0.51, 0.511, 0.5110 or etc.
I know I can easily achieve something like this:
var temp: Float = 3.511054256
var aStr = String(format: "%f", temp)
var arr: [AnyObject] = aStr.componentsSeparatedByString(".")
var tempInt: Int = Int(arr.last as! String)!
However, this gives me 511054. I'd like the option of retrieving any number of digits past the decimal point easily.
For a task I'm doing, I only need to retrieve the first 2 digits after the decimal point, but less restriction would be ideal.
Thanks.
You can specify the number of decimal digits, say N, in your format specifier as %.Nf, e.g., for 5 decimal digits, %.5f.
let temp: Float = 3.511054256
let aStr = String(format: "%.5f", temp).componentsSeparatedByString(".").last ?? "Unexpected"
print(aStr) // 51105
Alternatively, for a more dynamic usage, make use of an NSNumberFormatter:
/* Use NSNumberFormatter to extract specific number
of decimal digits from your float */
func getFractionDigitsFrom(num: Float, inout withFormatter f: NSNumberFormatter,
forNumDigits numDigits: Int) -> String {
f.maximumFractionDigits = numDigits
f.minimumFractionDigits = numDigits
let localeDecSep = f.decimalSeparator
return f.stringFromNumber(num)?.componentsSeparatedByString(localeDecSep).last ?? "Unexpected"
}
/* Example usage */
var temp: Float = 3.511054256
var formatter = NSNumberFormatter()
let aStr = getFractionDigitsFrom(temp, withFormatter: &formatter, forNumDigits: 5)
print(aStr) // 51105
Note that both solutions above will perform rounding; e.g., if var temp: Float = 3.519, then asking for 2 decimal digits will produce "52". If you really intend to treat your float temp purely as a String (with no rounding whatsoever), you could solve this using just String methods, e.g.
/* Just treat input as a string with known format rather than a number */
func getFractionDigitsFrom(num: Float, forNumDigits numDigits: Int) -> String {
guard let foo = String(temp).componentsSeparatedByString(".").last
where foo.characters.count >= numDigits else {
return "Invalid input" // or return nil, for '-> String?' return
}
return foo.substringWithRange(foo.startIndex..<foo.startIndex.advancedBy(numDigits))
}
/* Example usage */
let temp: Float = 3.5199
let aStr = getFractionDigitsFrom(temp, forNumDigits: 2) // 51
I want to write a Unicode string using hexadecimal values in Swift. I have read the documentation for String and Character so I know that I can use special Unicode characters directly in strings like the following:
var variableString = "Cat‼🐱" // "Cat" + Double Exclamation + cat emoji
But I would like to do it using the Unicode code points. The docs (and this question) show it for characters, but are not very clear about how to do it for strings.
(Note: Although the answer seems obvious to me now, it wasn't obvious at all just a short time ago. I am answering my own question below as a means of learning how to do this and also to help myself understand Unicode terminology and how Swift Characters and Strings work.)
Character
The Swift syntax for forming a hexadecimal code point is
\u{n}
where n is a hexadecimal number up to 8 digits long. The valid range for a Unicode scalar is U+0 to U+D7FF and U+E000 to U+10FFFF inclusive. (The U+D800 to U+DFFF range is for surrogate pairs, which are not scalars themselves, but are used in UTF-16 for encoding the higher value scalars.)
Examples:
// The following forms are equivalent. They all produce "C".
let char1: Character = "\u{43}"
let char2: Character = "\u{0043}"
let char3: Character = "\u{00000043}"
// Higher value Unicode scalars are done similarly
let char4: Character = "\u{203C}" // ‼ (DOUBLE EXCLAMATION MARK character)
let char5: Character = "\u{1F431}" // 🐱 (cat emoji)
// Characters can be made up of multiple scalars
let char7: Character = "\u{65}\u{301}" // é = "e" + accent mark
let char8: Character = "\u{65}\u{301}\u{20DD}" // é⃝ = "e" + accent mark + circle
Notes:
Leading zeros can be added or omitted
Characters are known as extended grapheme clusters. Even when they are composed of multiple scalars, they are still considered a single character. What is key is that they appear to be a single character (grapheme) to the user.
TODO: How to convert surrogate pair to Unicode scalar in Swift
String
Strings are composed of characters. See the following examples for some ways to form them using hexadecimal code points.
Examples:
var string1 = "\u{0043}\u{0061}\u{0074}\u{203C}\u{1F431}" // Cat‼🐱
// pass an array of characters to a String initializer
let catCharacters: [Character] = ["\u{0043}", "\u{0061}", "\u{0074}", "\u{203C}", "\u{1F431}"] // ["C", "a", "t", "‼", "🐱"]
let string2 = String(catCharacters) // Cat‼🐱
Converting Hex Values at Runtime
At runtime you can convert hexadecimal or Int values into a Character or String by first converting it to a UnicodeScalar.
Examples:
// hex values
let value0: UInt8 = 0x43 // 67
let value1: UInt16 = 0x203C // 8252
let value2: UInt32 = 0x1F431 // 128049
// convert hex to UnicodeScalar
let scalar0 = UnicodeScalar(value0)
// make sure that UInt16 and UInt32 form valid Unicode values
guard
let scalar1 = UnicodeScalar(value1),
let scalar2 = UnicodeScalar(value2) else {
return
}
// convert to Character
let character0 = Character(scalar0) // C
let character1 = Character(scalar1) // ‼
let character2 = Character(scalar2) // 🐱
// convert to String
let string0 = String(scalar0) // C
let string1 = String(scalar1) // ‼
let string2 = String(scalar2) // 🐱
// convert hex array to String
let myHexArray = [0x43, 0x61, 0x74, 0x203C, 0x1F431] // an Int array
var myString = ""
for hexValue in myHexArray {
if let scalar = UnicodeScalar(hexValue) {
myString.append(Character(scalar))
}
}
print(myString) // Cat‼🐱
Further reading
Strings and Characters docs
Glossary of Unicode Terms
Strings in Swift
Working with Unicode code points in Swift
from your Hex "0x1F52D" to actual Emoji
let c = 0x1F602
next step would possibly getting an Uint32 from your Hex
let intEmoji = UnicodeScalar(c!).value
from this you can do something like
titleLabel.text = String(UnicodeScalar(intEmoji)!)
here you have a "😂"
it work with range of hexadecimal too
let emojiRanges = [
0x1F600...0x1F636,
0x1F645...0x1F64F,
0x1F910...0x1F91F,
0x1F30D...0x1F52D
]
for range in emojiRanges {
for i in range {
let c = UnicodeScalar(i)!.value
data.append(c)
}
}
to get multiple UInt32 from your Hex range for exemple