I've written a small class that uses AVFoundation to play audio using an array. Basically an new element is appended to the array every time 'playAudio' is called. This allows multiple sounds to play without cutting each other off. Also, so that the array doesn't infinitely increase in size I've set it to cycle back to index 0 after filling 5 slots in the array. Now everything works perfectly but after 'audioPlayer' has been called a bunch of times, audio suddenly stops and I start getting the 'Error' in the Catch section but my app continues to function normally as if it has just been muted. Can anyone tell me why this is happening?
var audioIndexA = 0
public class AudioPlayer: NSObject {
var playerA = [AVAudioPlayer]()
func playAudio(audioFile audioFile: String){
do{
let path = NSBundle.mainBundle().pathForResource(audioFile, ofType:"wav")
let fileURL = NSURL(fileURLWithPath: path!)
playerA.insert(try AVAudioPlayer(contentsOfURL: fileURL, fileTypeHint: nil), atIndex: audioIndexA)
playerA[audioIndexA].prepareToPlay()
if audioIndexA < 5{
playerA[audioIndexA].play()
audioIndexA++
} else{
playerA[audioIndexA].play()
audioIndexA = 0
}
} catch{
print("Error")
}
}
}
Related
I´m looking for a way to make an array of urls from the contents of a folder containing soundfiles so that i can call them up with AVAudioplayer later.
I use a stepper and 3 variables,
the first one is called nmbTracks to define the number of playable soundfiles, and holds the steppers maxvalue
the second is called currentActiveTrack and defines which file the player should be playing.
the 3rd one is called audioURL and is used to feed the player aswell as retrieving the name of of the file which gets outputed to a label.
the user can then step through the soundfiles with the stepper.
so far I got everything working with some files that i have but I can´t figure out how to make an array of urls nor how to get urls from the contents of a folder, next step is to let the user import their own files into that folder.
any help would be greatly appreciated, I´m sure there is an easier way to do this aswell
I have a couple of options. The first one returns an array of URLs and if there is an error fetching the folder returns an empty array.
func getFolderContentsURLs(_ folderPath: String) -> [URL] {
let fm = FileManager()
guard let contents = try? fm.contentsOfDirectory(atPath: folderPath) else { return [] }
return contents.compactMap { URL.init(fileURLWithPath: $0) }
}
You can display the result like this:
let songsURLs = getFolderContentsURLs("/")
songsURLs.forEach {
print($0.absoluteString)
}
The second option return an optional array of URLs, on error returns nil
func getFolderContentsURLsOrNil(_ folderPath: String) -> [URL]? {
let fm = FileManager()
guard let contents = try? fm.contentsOfDirectory(atPath: folderPath) else { return nil }
return contents.compactMap { URL.init(fileURLWithPath: $0) }
}
To go through the results you can do it like this:
if let songsURLs2 = getFolderContentsURLsOrNil("NotExistingPath") {
songsURLs2.forEach {
print($0.absoluteString)
}
} else {
print("Unable to fetch contents")
}
Responding to #user12184258 comment about returning only audio files you can apply a filter after getting the folder contents. The filter can check each file using UTTypeConformsTo from MobileCoreServices
let contentsFolder = getFolderContentsURLs("/path/to/folder")
let audioFiles = contentsFolder
.filter { path in
// Try to create uniform type identifier using file's extension
guard let uti =
UTTypeCreatePreferredIdentifierForTag(
kUTTagClassFilenameExtension,
path.pathExtension as CFString, nil) else { return false }
// Checks conformance of UTI with kUTTypeAudio (abstract type for audio)
return UTTypeConformsTo((uti.takeRetainedValue()), kUTTypeAudio)
}
I found this method here. Also Apple has a very useful System-Declared Uniform Type Identifiers you can check, if you want only mp3 files you can use kUTTypeMP3.
I have text file which contains 18000 lines which have cities names. Each line has city name, state, latitude, longitude etc. Below is the function which does that, if i don't implement string.components(separtedBy: ", ") loading function is pretty fast but with it implemented it takes time which makes my UI freeze. What is the right way of doing it? Is string.components(separtedBy: ", ") that costly?
I profiled the app, this line is taking string.components(separtedBy: ", ") 1.45s out of 2.09s in whole function.
func readCitiesFromCountry(country: String) -> [String] {
var cityArray: [String] = []
var flag = true
var returnedCitiesList: [String] = []
if let path = Bundle.main.path(forResource: country, ofType: "txt") {
guard let streamReader = StreamReader(path: path) else {fatalError()}
defer {
streamReader.close()
}
while flag {
if let nextLine = streamReader.nextLine() {
cityArray = nextLine.components(separatedBy: ",") // this is the line taking a lot of time, without this function runs pretty fast
if (country == "USA") {
returnedCitiesList.append("\(cityArray[0]) , \(cityArray[1]) , \(cityArray[2])")
} else {
returnedCitiesList.append("\(cityArray[0]) , \(cityArray[1])")
}
//returnedCitiesList.append(nextLine)
} else {
flag = false
}
}
} else {
fatalError()
}
return returnedCitiesList
}
StreamReader used in the code can be found here. It helps to read file line by line
Read a file/URL line-by-line in Swift
This question is not about how to split the string into array Split a String into an array in Swift? , rather why splitting is taking more time in the given function.
NSString.components(separatedBy:) returns a [String], which requires that all of the pieces' content be copied, from the original string, and pasted into new-ly allocated stringss. This slows things down.
You could address the symptoms (UI freezing) by putting this work on a background thread, but that just sweeps the problem under the wrong (the inefficient copying is still there), and complicates things (async code is never fun).
Instead, you should consider using String.split(separator:maxSplits:omittingEmptySubsequences:), which returns [Substring]. Each Substring is just a view into the original string's memory, which stores the relevant range so that you only see that portion of the String which is modeled by the Substring. The only memory allocation happening here is for the array.
Hopefully that should be enough to speed your code up to acceptable levels. If not, you should combine both solutions, and use split off-thread.
I have an empty global array. The only simple thing I want to do is add an element to this array. It seems in swift this seemingly simple task is proving to be difficult. I am just left with an empty array and nothing is appending to my global array.
I can see that it prints out values in the for loop. So the values are actually there.
This is some stuff I have declared globally (Yes, I know global variables are bad but I will sort that out later):
struct HouseDetails: Decodable {
let median_price: String
let sale_year: String
let transaction_count: String
let type: String
}
var hsArray: [HouseDetails] = []
and in the viewDidLoad() function I have the data which I am storing in local variable "houses". When I loop through the array it prints median_price, showing that the values are there.
However when I do hsArray.append(h) it seems to do nothing.
let jsonUrlString = "https://data.melbourne.vic.gov.au/resource/i8px-csib.json"
guard let url = URL(string: jsonUrlString)
else { return }
URLSession.shared.dataTask(with: url) { (data, response, err) in
guard let data = data else { return }
do {
let houses = try JSONDecoder().decode([HouseDetails].self, from: data)
for h in houses {
hsArray.append(h)
print(h.median_price)
}
}
catch let jsonErr {
print("Error with json serialization", jsonErr)
}
}.resume()
Thank you for any help. In other languages I am used to being able to append an element to the end of an existing array, so I am sure it is just a small error.
Firstly, why don't you simply do
hsArray.append(contentsOf: houses)
instead of all that for loop
for h in houses {
hsArray.append(h)
print(h.median_price)
}
The issue might be the time at which you are using hsArray. See if the response is received after you use hsArray.
I am facing the problem that I fill up an array with data and when I want to remove it later, even though I call the removeAll() the array still is not empty.
Better see my code for a more clear view on the problem
Updated new code
#objc func textFieldDidChange() {
doSearch()
if let commentText = commentTextField.text , !commentText.isEmpty {
sendButton.setTitleColor(UIColor.blue, for: UIControlState.normal)
sendButton.isEnabled = true
return
}
sendButton.setTitleColor(UIColor.lightGray, for: UIControlState.normal)
sendButton.isEnabled = false
}
func doSearch() {
let caption = commentTextField.text
let words = caption?.components(separatedBy: CharacterSet.whitespacesAndNewlines)
self.usersSuggestion.removeAll()
for var word in words! {
self.usersSuggestion.removeAll()
if word.hasPrefix("#") {
word = word.trimmingCharacters(in: CharacterSet.punctuationCharacters)
self.isCellSelected = true
self.usersSuggestion.removeAll()
API.User.suggestUsers(withText: word, completion: { (user) in
print("closure", word)
self.usersSuggestion.append(user)
self.tableView.reloadData()
print("#", self.usersSuggestion.count)
})
self.usersSuggestion.removeAll()
tableView.reloadData()
} else {
self.isCellSelected = false
self.usersSuggestion.removeAll()
tableView.reloadData()
}
self.usersSuggestion.removeAll()
tableView.reloadData()
}
}
I am facing the problem here that the array, even though I call multiple times the removeAll() method, never gets back to 0. When I have 2 user, link one, the next time I write an # I get the 2 users+ the linked user (so him twice). I can do it infinitely, having like 100 userSuggestions with just 2 existing users.
photos
You are printing the count immediately after inserting an element in the array. This will alway give a count of 1.
// count was zero
self.hashTags.insert(hashTag, at: 0) // adding one
print("# = ", self.hashTags.count) // count is now 1
Given that the API.user... function uses a completion handler, I would assume that this happens in a separate thread or at least asynchronously so you could event get into situations where the UI shows empty and suddenly shows one.
You may want to structure your code differently to better convey the separation between requesting data and displaying the (asynchronously obtained) results. Embedded completion handlers tend be misleading and give the impression that execution will happen in their visually organized sequence.
I'm trying to create a function in Xcode that I can call every time I hit a button to iterate through an array in sequence which then updates the value of the button title.
I can't seem to crack the challenge. I've tried various iterations of while loops and if statements but everytime I run it I end straight up at the last value in the array. Here's the code I've got at the moment, I tried to add a break clause to stop the function from automatically iterating through the whole array but it's now throwing up an error message saying that the code after the return statement will never be executed:
So, I've created an instance of a button within my viewController as follows:
#IBAction func repCount() {
repCountButton.setTitle("\(repCounter.repCount())", forState: UIControlState.Normal)
I'm hoping that this will then update the title of the button with what I return from the repCount function that is called every time the button is pressed.
I've set up the function in a separate Swift file called repCounter and my code for the repCount function is as follows:
var repArray = [1,2,3,4,5]
var repArrayIndex: Int = 0
func repCount () -> String {
if repArrayIndex < repArray.count {
while repArrayIndex < repArray.count {
return "\(repArray[repArrayIndex])"
break
}
repArrayIndex++
} else {
return "\(repArray[0])"
}
}
What I'd like this to do is to cycle through the array every time it is called and once it's got to the end of the array to start cycling from the beginning of the array again.
Thanks in advance for any help!
I'm not at a computer where I can pull up XCode to test it, but I think the version below will do what you want. It isn't the most elegant code, but it is very straightforward. You have to do all the index juggling before the return statement since once the code hits a return, nothing following it will be executed.
I added some code to reset the index once it reaches the end of the array.
var repArray = [1,2,3,4,5]
var repArrayIndex: Int = 0
func repCount () -> String {
while repArrayIndex < repArray.count {
var curIndex = repArrayIndex
repArrayIndex = repArrayIndex + 1;
if repArrayIndex >= repArray.count {
repArrayIndex = 0
}
return "\(repArray[curIndex])"
}
return "\(repArray[0])"
}
Another option to getting this count, without iterating, is to do
// From Swift 1.2
func repCount () -> String {
return count(repArray)
}
// Before Swift 1.2
func repCount () -> String {
return countElements(repArray)
}
If you insist on iterating there are multiple options, see Iterating over an array, one which could be:
var count = 0
for rep in repArray {
count++
}
Or you could for the round trip iteration provided in the other answer, but why do it the hard way, when you don't need to? Or is there something you haven't told us?