So essentially, I'm using a server to retrieve the URLs already stored. Once I retrieve the URL (in a for loop), I am calling a function that downloads them directly from AWS S3. The issue is that when I only have to download one image at a time, it works perfectly; this includes the case where I am already downloading one image, I upload another, then I go back to the loading home view, and the two images appear properly. When I have multiple images that need downloading (when I first start the app), the images array overlaps. I am using an array for the URL and another array for the UIImages.
Here is my ImageCache code:
class ImageCache {
static var urlCache: Array<String> = []
static var imageCache: Array<UIImage> = []
}
I used this instead of NSCache is because I need to be able to use imageCache as my data source and I wasn't sure how to specify the number of objects inside an NSCache as a NSCache object isn't iterable.
Anyways, here is the code where I'm calling the download function:
query.findObjectsInBackground { (results, error) in
var imageURL: String = ""
var count: Int = 1
if error == nil {
for result in results! {
print(result)
imageURL = result["imageURL"] as! String
let imageKey = imageURL.components(separatedBy: "/uploads")[1]
if !ImageCache.urlCache.contains(imageURL) {
self.downloadImageFromS3(key: "uploads\(imageKey)", count: results!.count, current: count, url: imageURL)
}
count += 1
}
}
}
The reason for current and count is that when the current index equals the last index in the for loop, then we should update the UICollectionView. This way the view is reloaded only when the last image is downloaded (at least this was the goal).
And here is my downloadImageFromS3 function:
func downloadImageFromS3(key: String, count: Int, current: Int, url: String) {
DispatchQueue.main.async {
let transferManager = AWSS3TransferManager.default()
let downloadingFileURL = URL(fileURLWithPath: NSTemporaryDirectory()).appendingPathComponent("image.png")
let downloadRequest = AWSS3TransferManagerDownloadRequest()
downloadRequest!.bucket = "BUCKET_NAME"
downloadRequest!.key = key
downloadRequest!.downloadingFileURL = downloadingFileURL
transferManager.download(downloadRequest!).continueWith(executor: AWSExecutor.mainThread()) { (task) -> Any? in
if let error = task.error as NSError? {
if error.domain == AWSS3TransferManagerErrorDomain, let code = AWSS3TransferManagerErrorType(rawValue: error.code) {
switch code {
case .cancelled, .paused:
break
default:
print("Error downloading: \(String(describing: downloadRequest!.key)) Error: \(error)")
}
} else {
print("Error downloading: \(String(describing: downloadRequest!.key)) Error: \(error)")
}
return nil
} else {
let image = UIImage(contentsOfFile: downloadingFileURL.path)!
ImageCache.urlCache.append(url)
ImageCache.imageCache.append(image)
}
print("Download complete for: \(String(describing: downloadRequest!.key))")
if current == count && ImageCache.imageCache.count == count && ImageCache.urlCache.count == count {
self.collectionView?.reloadData()
print(ImageCache.imageCache)
print(ImageCache.urlCache)
}
return nil
}
}
}
EDIT: I thought I fixed the issue by putting the line
self.collectionView.reloadData()
outside that if statement I was explaining earlier. This causes the last two images to be messed with, meaning that the first and second image will look fine, but the third and fourth image are the same image. Does anyone have any solutions to make this work?
EDIT: I just found the real issue in why some of the final images are overlapping. I'm getting a decoding error when downloading the image:
2018-08-10 22:26:57.826759-0500 PROJECT_NAME[81557:49209786] mapData:754: *** ImageIO - mmapped file changed (old: 8112955 new: 6209998)
2018-08-10 22:26:57.871970-0500 PROJECT_NAME[81557:49209786] [0x7fcf610c5a00] Decoding failed with error code -1
2018-08-10 22:26:57.872127-0500 PROJECT_NAME[81557:49209786] [0x7fcf610c5a00] Decoding: C0 0x10C00B20 0x0218304A 0x11111100 0x00590011 8112955
2018-08-10 22:26:57.872225-0500 PROJECT_NAME[81557:49209786] [0x7fcf610c5a00] Options: 1x-1 [00000000,10C003B6] 0001D060
2018-08-10 22:26:57.872341-0500 PROJECT_NAME[81557:49209786] imageBlockSetCreate:829: *** buffer height mismatch: rect:{0,0,4288,950} size:{4288,2848}
2018-08-10 22:26:57.873336-0500 PROJECT_NAME[81557:49209786] [Unknown process name] img_blocks_create: Null block
CGImageProviderCopyImageBlockSet(<CGImageProvider 0x6040002ed980> (component-type = Int8, pixel-size = 4, size = [4288 x 2848]));
<CGImageBlockSet 0x6000001357c0> (size = [4288 x 2848], rect = (0, 0) x [4288, 950], count = 3) [1]
2018-08-10 22:26:57.873474-0500 PROJECT_NAME[81557:49209786] [Unknown process name] img_blocks_create: Null block
CGImageProviderCopyImageBlockSet(<CGImageProvider 0x6040002ed980> (component-type = Int8, pixel-size = 4, size = [4288 x 2848]));
<CGImageBlockSet 0x6000001357c0> (size = [4288 x 2848], rect = (0, 0) x [4288, 950], count = 3)
I'm under the impression that the error is in this line: let image = UIImage(contentsOfFile: downloadingFileURL.path)!. The image, upon upload to S3, has Content-Encoding set to base64.
Solved my own question. Once I changed the downloadingFileURL path to a .jpeg file path and made it unique, I was able to see the issue. I was also invoking the wrong initializer for UIImage. It should've been UIImage(named: downloadingFileURL.path)! instead of UIImage(contentsOfFile: downloadingFileURL.path)!
Related
I am getting error Thread 1: Fatal error: Index out of range on
func ReaderConverterCallback(_ converter: AudioConverterRef,
_ packetCount: UnsafeMutablePointer<UInt32>,
_ ioData: UnsafeMutablePointer<AudioBufferList>,
_ outPacketDescriptions: UnsafeMutablePointer<UnsafeMutablePointer<AudioStreamPacketDescription>?>?,
_ context: UnsafeMutableRawPointer?) -> OSStatus {
let reader = Unmanaged<Reader>.fromOpaque(context!).takeUnretainedValue()
//
// Make sure we have a valid source format so we know the data format of the parser's audio packets
//
guard let sourceFormat = reader.parser.dataFormat else {
return ReaderMissingSourceFormatError
}
//
// Check if we've reached the end of the packets. We have two scenarios:
// 1. We've reached the end of the packet data and the file has been completely parsed
// 2. We've reached the end of the data we currently have downloaded, but not the file
//
let packetIndex = Int(reader.currentPacket)
let packets = reader.parser.packets
let isEndOfData = packetIndex >= packets.count - 1
if isEndOfData {
if reader.parser.isParsingComplete {
packetCount.pointee = 0
return ReaderReachedEndOfDataError
} else {
return ReaderNotEnoughDataError
}
}
//
// Copy data over (note we've only processing a single packet of data at a time)
//
let packet = packets[packetIndex] <--------- Thread 1: Fatal error: Index out of range on
var data = packet.0
let dataCount = data.count
ioData.pointee.mNumberBuffers = 1
ioData.pointee.mBuffers.mData = UnsafeMutableRawPointer.allocate(byteCount: dataCount, alignment: 0)
_ = data.withUnsafeMutableBytes { (bytes: UnsafeMutablePointer<UInt8>) in
memcpy((ioData.pointee.mBuffers.mData?.assumingMemoryBound(to: UInt8.self))!, bytes, dataCount)
}
ioData.pointee.mBuffers.mDataByteSize = UInt32(dataCount)
//
// Handle packet descriptions for compressed formats (MP3, AAC, etc)
//
let sourceFormatDescription = sourceFormat.streamDescription.pointee
if sourceFormatDescription.mFormatID != kAudioFormatLinearPCM {
if outPacketDescriptions?.pointee == nil {
outPacketDescriptions?.pointee = UnsafeMutablePointer<AudioStreamPacketDescription>.allocate(capacity: 1)
}
outPacketDescriptions?.pointee?.pointee.mDataByteSize = UInt32(dataCount)
outPacketDescriptions?.pointee?.pointee.mStartOffset = 0
outPacketDescriptions?.pointee?.pointee.mVariableFramesInPacket = 0
}
packetCount.pointee = 1
reader.currentPacket = reader.currentPacket + 1
return noErr;
}
even if there is packetIndex is less then packets.count.
Note: Please compare both question before marking it duplicate. Reference possible duplicate doesn't show that index of array is less than array count.
I am using this https://github.com/syedhali/AudioStreamer/ library for playing audio from url.
It looks like a Multi-Thread problem. According to the printed logs, the index seems ok, but another thread may change the data 'packets', that causes the crash. Please consider locking data-related operations between threads.
Additional analyzation: according to the following lines, packets may be shared between threads.
let reader = Unmanaged<Reader>.fromOpaque(context!).takeUnretainedValue()
//......
let packets = reader.parser.packets
Suggestion: check if somewhere the Unmanaged<Reader> change the parser.packets, and make a lock strategy.
The input to dictionary(fromTXTRecord:) comes from the network, potentially from outside the app, or even the device. However, Apple's docs say:
... Fails an assertion if txtData cannot be represented as an NSDictionary object.
Failing an assertion leaves the programmer (me) with no way of handling the error, which seems illogic for a method that processes external data.
If I run this in Terminal on a Mac:
dns-sd -R 'My Service Name' _myservice._tcp local 4567 asdf asdf
my app, running in an iPhone, crashes.
dictionary(fromTXTRecord:) expects the TXT record data (asdf asdf) to be in key=val form. If, like above, a word doesn't contain any = the method won't be able to parse it and fail the assertion.
I see no way of solving this problem other than not using that method at all and implementing my own parsing, which feels wrong.
Am I missing something?
Here's a solution in Swift 4.2, assuming the TXT record has only strings:
/// Decode the TXT record as a string dictionary, or [:] if the data is malformed
public func dictionary(fromTXTRecord txtData: Data) -> [String: String] {
var result = [String: String]()
var data = txtData
while !data.isEmpty {
// The first byte of each record is its length, so prefix that much data
let recordLength = Int(data.removeFirst())
guard data.count >= recordLength else { return [:] }
let recordData = data[..<(data.startIndex + recordLength)]
data = data.dropFirst(recordLength)
guard let record = String(bytes: recordData, encoding: .utf8) else { return [:] }
// The format of the entry is "key=value"
// (According to the reference implementation, = is optional if there is no value,
// and any equals signs after the first are part of the value.)
// `ommittingEmptySubsequences` is necessary otherwise an empty string will crash the next line
let keyValue = record.split(separator: "=", maxSplits: 1, omittingEmptySubsequences: false)
let key = String(keyValue[0])
// If there's no value, make the value the empty string
switch keyValue.count {
case 1:
result[key] = ""
case 2:
result[key] = String(keyValue[1])
default:
fatalError()
}
}
return result
}
I'm still hoping there's something I'm missing here, but in the mean time, I ended up checking the data for correctness and only then calling Apple's own method.
Here's my workaround:
func dictionaryFromTXTRecordData(data: NSData) -> [String:NSData] {
let buffer = UnsafeBufferPointer<UInt8>(start: UnsafePointer(data.bytes), count: data.length)
var pos = 0
while pos < buffer.count {
let len = Int(buffer[pos])
if len > (buffer.count - pos + 1) {
return [:]
}
let subdata = data.subdataWithRange(NSRange(location: pos + 1, length: len))
guard let substring = String(data: subdata, encoding: NSUTF8StringEncoding) else {
return [:]
}
if !substring.containsString("=") {
return [:]
}
pos = pos + len + 1
}
return NSNetService.dictionaryFromTXTRecordData(data)
}
I'm using Swift 2 here. All contributions are welcome. Swift 3 versions, Objective-C versions, improvements, corrections.
I just ran into this one using Swift 3. In my case the problem only occurred when I used NetService.dictionary(fromTXTRecord:) but did not occur when I switched to Objective-C and called NSNetService dictionaryFromTXTRecord:. When the Objective-C call encounters an entry without an equal sign it creates a key containing the data and shoves it into the dictionary with an NSNull value. From what I can tell the Swift version then enumerates that dictionary and throws a fit when it sees the NSNull. My solution was to add an Objective-C file and a utility function that calls dictionaryFromTXTRecord: and cleans up the results before handing them back to my Swift code.
I'm looking for a fast, optimized way to trim log files on iOS. I want to specify that my log files have a maximum number of lines (e.g., 10,000). Appending new lines to the end of a text file seems relatively simple. However, I haven't yet found a fast way to trim lines at the beginning of the file. Here's the (slow) code I came up with.
guard let fileURL = self.fileURL else {
return
}
guard let path = fileURL.path else {
return
}
guard let fileHandle = NSFileHandle(forUpdatingAtPath: path) else {
return
}
fileHandle.seekToEndOfFile()
fileHandle.writeData(message.dataUsingEncoding(NSUTF8StringEncoding)!)
fileHandle.writeData("\n".dataUsingEncoding(NSUTF8StringEncoding)!)
currentLineCount += 1
// TODO: This could probably use some major optimization
if currentLineCount >= maxLineCount {
if let fileString = try? NSString(contentsOfURL: fileURL, encoding: NSUTF8StringEncoding) {
var lines = fileString.componentsSeparatedByCharactersInSet(NSCharacterSet.newlineCharacterSet())
lines.removeFirst()
let newData = lines.joinWithSeparator("\n")
fileHandle.seekToFileOffset(0)
fileHandle.writeData(newData.dataUsingEncoding(NSUTF8StringEncoding)!)
}
}
fileHandle.closeFile()
There are two aspects of your question. First, your code removes a single
line from the log file. Therefore, once the limit is reached, every new
log message causes the entire file to be read, shortened, and be re-written.
It would be more effective to use a "high-water mark" and a "low-water mark". For example, if you want the last 10.000 lines to be preserved,
let the log file grow until it has 15.000 lines, and only then truncate
it to 10.000 lines. This reduces the number of "trim actions"
considerably.
The second part is about the truncating itself. Your code loads the
file into an NSString, which requires the conversion of UTF-8 data
to Unicode characters
(and fails if there is a single invalid byte in the log file).
Then the string is split into an array, one array element removed,
the array concatenated to a string again, and then written back
to the file, which converts the Unicode characters to UTF-8.
I haven't done performance tests, but I can imagine that it could be
faster to operate on binary data only, without the conversions to
NSString, Array and back. Here is a possible implementation
which removes a given number of lines from the start of a file:
func removeLinesFromFile(fileURL: NSURL, numLines: Int) {
do {
let data = try NSData(contentsOfURL: fileURL, options: .DataReadingMappedIfSafe)
let nl = "\n".dataUsingEncoding(NSUTF8StringEncoding)!
var lineNo = 0
var pos = 0
while lineNo < numLines {
// Find next newline character:
let range = data.rangeOfData(nl, options: [], range: NSMakeRange(pos, data.length - pos))
if range.location == NSNotFound {
return // File has less than `numLines` lines.
}
lineNo++
pos = range.location + range.length
}
// Now `pos` is the position where line number `numLines` begins.
let trimmedData = data.subdataWithRange(NSMakeRange(pos, data.length - pos))
trimmedData.writeToURL(fileURL, atomically: true)
} catch let error as NSError {
print(error.localizedDescription)
}
}
I have updated Martin R answer to Swift 3, and I also changed it so that we can pass the number of lines to keep instead of the number of lines to remove:
func removeLinesFromFile(fileURL: URL, linesToKeep numLines: Int) {
do {
let data = try Data(contentsOf: fileURL, options: .dataReadingMapped)
let nl = "\n".data(using: String.Encoding.utf8)!
var lineNo = 0
var pos = data.count-1
while lineNo <= numLines {
// Find next newline character:
guard let range = data.range(of: nl, options: [ .backwards ], in: 0..<pos) else {
return // File has less than `numLines` lines.
}
lineNo += 1
pos = range.lowerBound
}
let trimmedData = data.subdata(in: pos..<data.count)
try trimmedData.write(to: fileURL)
} catch let error as NSError {
print(error.localizedDescription)
}
}
Instead of writing the new line to the log, and processing the appended content afterwards, do both write and trimming in one step:
let fileString = (try? NSString(contentsOfURL: fileURL, encoding: NSUTF8StringEncoding)) as NSString? ?? ""
var lines = fileString.characters.split("\n").map{String($0)}
lines.append(message)
// this also more generic as it will remove any number of extra lines
lines.removeFirst(max(currentLineCount - maxLineCount), 0))
let newLogContents = lines.joinWithSeparator("\n")
(newLogContents as NSString).writeToURL(fileURL, atomically: true, encoding: NSUTF8StringEncoding)
I try to add bytes with bytes in order to get space that will be occupied by photos which i retrieve from internet.
I have following code, it gets sizes in bytes for each id in array of id
var diskSpace:Int64 = 0
for var i = 0; i < array.count; i++ {
let id = array[i]
let urlString = "urlToFetchData"
if let url = NSURL(string: urlString) {
if let data = try? NSData(contentsOfURL: url, options: []) {
let json = JSON(data: data)
let size = Int64(json["size"].stringValue)
diskSpace = diskSpace + size!
}
}
}
var diskSpaceInMb = diskSpace / 1024 / 1024
print("diskSpaceInMb is \(diskSpaceInMb)")
for example, I try to get size of three elements, which have following size in bytes (these sizes in bytes I receive in json)
3223653
5855382
8948976
when the code above is executed i receive result of
diskSpaceInMb is 8
which is obviously not try
How to convert bytes to megabytes correctly ?
let fileSizeWithUnit = ByteCountFormatter.string(fromByteCount: diskSpace, countStyle: .file)
print("File Size: \(fileSizeWithUnit)")
The problem is obviously in the for loop. Maybe the JSON is not as you expect.
Another reason why this might fail is the you use the try? keyword, which in this context it means that it gives you a value if it succeeds, but otherwise it returns nil. In your case, it may silently fail. If you want to check if it fails, you could add an else branch.
I keep getting this error :
fatal error: unexpectedly found nil while unwrapping an Optional value
and cannot figure out how to debug it!
Here's my code :
func readCSV() -> Array<String> {
// Creates a new array of strings
var csvArray : Array<String> = Array<String>()
if let url: NSURL = NSURL(string : "URLFROMCSV" ) {
// Creates an Input Stream that will load the datas from our URL
let data :NSData! = NSData(contentsOfURL: url)!
let stream : NSInputStream! = NSInputStream(data: data)
// Opens the receiving stream
stream.open()
// Sets a buffer with a given size size
let bufferSize = 1024
var buffer = Array <UInt8>(count: bufferSize, repeatedValue: 0)
// String variable initialization
var csvFullString : String = ""
// While the stream receives datas, parses datas, convert them into strings and then concatenate them into one big string
while (stream.hasBytesAvailable) {
let readSize = stream.read(&buffer, maxLength: bufferSize)
let csvRaw = NSString (bytes: &buffer, length: readSize, encoding: NSUTF8StringEncoding)
let csvString = csvRaw as String!
csvFullString = csvFullString + csvString
}
// Fills the array with each strings. Separation between strings is made when a Θ character is parsed
csvArray = csvFullString.componentsSeparatedByString("Θ")
// Delete each null string
for(var i = 0 ; i < csvArray.count; i++) {
if(csvArray[i] == "") {
csvArray.removeAtIndex(i)
}
}
}
return csvArray
}
After searching on the web, I'm pretty sure it has something to do with unwrapping elements but the fact is when I debug it, i don't get any nil value anywhere.
PS: Would like to upload a screen but can't because i don't have 10 reputation, so bad!
Thanks in advance!
EDIT : Line let data :NSData! = NSData(contentsOfURL: url)! got the error.
Terry
You're probably creating the error in one of these two lines (though it may show up later):
let data :NSData! = NSData(contentsOfURL: url)!
let stream : NSInputStream! = NSInputStream(data: data)
You're assigning an optional value to an implicitlyUnwrappedOptional type and then using it without checking if you have a valid value.
This is why if let exists. It's a little funny that you've started to indent as if you're using if let but aren't.
Try this instead:
if let url = NSURL(string : "http://gorillaapplications.com/etablissements.csv" ) {
// Creates an Input Stream that will load the datas from our URL
if let data = NSData(contentsOfURL: url) {
let stream = NSInputStream(data: data)
stream.open()
// rest of your code here
}
else {
println("Didn't get a data object")
}
}
else {
println("Didn't get a URL object")
}
You really need to grasp Optionals for Swift. I'd recommend reading my Optionals chapter in this iBook: https://itunes.apple.com/us/book/swift-optionals-generics-for/id943445214?mt=11&uo=4&at=11lMGu
Update:
Since you added a bit more in your comments above, you're saying you get the error on this line: let data: NSData! = NSData(contentsOfURL: url)!. This is because of the ! at the end, which tells Swift you're sure that this function will return a valid value, so just use it, without checking if it's nil first. In your case, the function is returning nil and so your app crashes. Using the sample code I've provided above, you'll see that you'll no longer get a crash, but your code will execute the "Didn't get a data object" line. You'll need to correctly handle the case where you can't load data from that URL.