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Day 29

Saurabh Jamadagni
25th July, 2022

Lists

  • They are the equivalent to UITableView from UIKit.
  • Job of lists is to provide a scrolling table of data.

    Pro tip: If your section header is just a string, you can just pass it as Section("string")

  • By default, lists will look very similar to forms. But lists can be styled.
  • Lists can generate their own rows dynamically without a ForEach in place unlike Forms.

App bundles

  • XCode takes all our assets, text files, etc. and stores them inside an app bundle.
  • How do you access these files then?
  • These are done using a local URL inside the bundle.
  • It has to be optionally unwrapped as there is a change a file may not exist.
if let fileURl = Bundle.main.url(forResource: "some-file", extension: "txt") {
    // what you wanna do with the file.
}
  • This is called as sandboxing, where we have our main app bundle and mini bundles associated.
  • We can then access the contents of the file using
if let fileContents = try? String(contentsOf: fileURL) {
    // fileContents is a string.
}

Working with strings

  • Several APIs are available to work with strings that allow us to break strings into arrays, get rid of whitespaces and even check for spellings!
  • We can use components(separatedBy: "\n") to break strings into an array of lines.
  • We can check spellings using UITextChecker. It is part of Apple's old framework UIKit and thus has a different method of utilising it.
    • First create an object of the UITestChecker class.
    • Second, we have to tell our checker how much of our string we wish to check.
    • Swift can handle complex characters like emojis, but Objective-C can't.
    • To create the range, we use NSRange and have to provide the encoding to bridge between Swift and Objective-C
    • In checking mispelled words, we have provide the word, the range, starting point, if it should wrap back to the first mispelled check and the language.
    • Use code completions for this. No way you can exactly get the exact parameter list and or order.
func test() {
    let word = "swift"
    let checker = UITextChecker()
    // the utf16 is the encoding we mention
    let range = NSRange(location: 0, length: word.utf16.count)

    let misspelledRange = checker.rangeOfMisspelledWord(in: word, range: range, startingAt: 0, wrap: false, language: "en")

    // because Objective-C does not have the concepts such as optional
    // if the misspelled range is empty, a NSNotFound is returned.
    // check for that
    let allGood = misspelledRange.location == NSNotFound
}

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