nsdata

问题 Is there anyway I can look at the size of a file the application creates in bytes then store that number to use later? OR is there any way I can tell if an object in an NSArray is empty, I've tried everything, but it just doesn't work! 回答1: Use NSFileManager class' method - (NSDictionary *)attributesOfItemAtPath:(NSString *)path error:(NSError **)error The size key in the returned dictionary is defined as NSString * const NSFileSize; So for an example NSError *error = nil; NSDictionary

问题 I have a requirement in which the user can select an image from camera roll and my application needs to optimize the image and upload it to a server. I am using ALAssets library and a custom picker for the user to select a photo from camera roll . I am able to achieve this perfectly but have a problem with the file size getting increased. The problem is as follows: When the user selects a photo, of 1.7MB (That is the full size as reported by the iOS when I try to mail the photo), when I

问题 I have a simple NSString and I'm converting it to NSData : NSData *data = [[NSData dataWithBytes:[[NSString stringWithFormat:@",%@",self.targetId] dataUsingEncoding:NSASCIIStringEncoding] length:[[NSString stringWithFormat:@",%@",self.targetId] lengthOfBytesUsingEncoding:NSASCIIStringEncoding]] retain]; Now I want to get the plain text from the NSData object. If I'm doing that : NSString* dataStr = [NSString stringWithFormat:@"%@",data]; - I'm getting just an hex expression (i.e <9c3f473e

问题 I am interfacing with a hardware device that streams data to my app over Wifi. The data is streaming in just fine. The data contains a character header (DATA:) that indicates a new record has begun. The issues is that the data I receive doesn't necessarily fall on the header boundary, so I have to capture the data until what I've captured contains the header. Then, everything that precedes the header goes into the previous record and everything that comes after it goes into a new record. I

问题 I have a question concerning the use of AVFoundation’s AVPlayer (probably applicable to both iOS and macOS). I am trying to playback audio (uncompressed wav) data that come from a channel other than the standard HTTP Live Streaming. The case: Audio data packets come compressed in a channel along with other data the app needs to work with. For example, video and audio come in the same channel and get separated by a header. After filtering, I get the audio data and decompress them to a WAV

问题 I'm trying to understand how structs work within SWIFT. I'm familiar with how .NET handles them and how it packs bytes into a structure, etc. I'm finding some weirdness with the following code: struct exampleStruct { var ModelNumber: Byte! var MajorVersion: Byte! var MinorVersion: Byte! var Revision: Byte! } var myStruct = exampleStruct ( ModelNumber: 1, MajorVersion: 2, MinorVersion: 3, Revision: 4 ) myStruct.MinorVersion // << Returns 3 // Struct to NSData. var data = NSData( bytes:

问题 I've been having issues converting an Objective-C snippet to Swift that uses NSData and CoreBluetooth . I have looked at this question and a couple others dealing with NSData in Swift but haven't had any success. Objective-C Snippet: - (CGFloat) minTemperature { CGFloat result = NAN; int16_t value = 0; // characteristic is a CBCharacteristic if (characteristic) { [[characteristic value] getBytes:&value length:sizeof (value)]; result = (CGFloat)value / 10.0f; } return result; } What I have so

问题 The code below works for downloading a single image from a url. func imageForImageURLString(imageURLString: String, completion: (image: UIImage?, success: Bool) -> Void) { guard let url = NSURL(string: imageURLString), let data = NSData(contentsOfURL: url), let image = UIImage(data: data) else { completion(image: UIImage(named:"absolut5.png"), success: false); return } completion(image: image, success: true) } however some of the urls I am working with are a zipped folder with several png

问题 This question already has answers here : Converting HEX NSString To NSData (4 answers) Closed 5 years ago . I've been trying to convert a user defaults NSString (tried NSData also), into a hex value I can use with char array. the problem is that every time I convert it from the NSString or NSData it takes the hex values and turns them into ASCII values, which isn't what I want at all. how to I tell it to literally take the values that are there and keep them hex? I'm struggling to find a

问题 I am trying to upload a video to a server file through Alamofire but I couldn't get the "data" going to be passed..its always nil var videoURL = NSURL(string: "") //returns Optional(file:///private/var/mobile/Containers/Data/Application/1FB40086-228B-4011-A9D4-7874E2EEF9F4/tmp/4A6AAD76-B899-4B67-8E96-925DA4AE9E93.mov) let videodata = NSData(contentsOfFile: (videoURL?.absoluteString)!) //nil let url = NSURL(fileURLWithPath: (videoURL?.absoluteString)!) let videodata = NSData(contentsOf: url as