What I've known:
How make requests to server for uploading I will use AFNetworking
How access photos and videos with help of ALAssetsLibrary
I think I must use CoreData to keep info about:last syncing, photos already uploaded, etc. I worked already with coreData it will no be a problem.
My problems are logic, flow how can achieve this auto back up and of course to be optimum(minimum requests, short way). What steps must follow to achieve this scope?
Any thoughts?
I think CoreData is too heavy in this situation. You may want to use plist to store your info data .here are some steps to follow .
After loading image from server, create a dictionary to store the message you want and create another dictionary to store these messages , and use image's url as the key of this dictionary. It might look like this:
imageUrl = {
lastSyncTime = xxxxxxxxxx,
photoUploaded = 0,
}
Create a plist file to save this dictionary:
- (NSString *)filePath:(NSString *) fileName{
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
return [documentsDirectory stringByAppendingPathComponent:fileName];
}
[yourImageDictionary writeToFile:[self filePath:#"imageInfo.plist"] atomically:YES];
Read or write your plist file anytime you want:
if ([[NSFileManager defaultManager] fileExistsAtPath:[self filePath:#"imageInfo.plist"]]) {
NSDictionary *imageInfo = [NSDictionary dictionaryWithContentsOfFile:[self filePath:#"imageInfo.plist"]];
}
Related
even after so many research i haven't found a solution for this question. I am currently working on a app which uses 3 view controllers for Registration with a log out button. the last view controller has the Register button which saves all the details of registration in a web service. But if the user has filled the two view forms and logs out. The two view filled forms field should be saved in the local memory and wen the user logs it again the pre filled forms should load the fields saved in internal memory just to continue the Registration for webservice. Any idea how to implement this sort of functionality
As others have said, NSUserDefaults will suffice for what you need.
NSUserDefaults *registrationInfo = [NSUserDefaults standardUserDefaults];
Guessing you have text fields with the info you need. So pull out the text and save to a key like this.
[registrationInfo setObject:self.someTextFieldName.text forKey#"firstTextField"];
After repeating this for every text field(use different key names though), call this [registrationInfo synchronize];
To pull the data out, you open the defaults again just like the first line. And to retrieve a specific key: NSString *firstTextField = [registrationInfo objectForKey:#"firstTextField"];
To make this easier, you can also put all of your strings in an array or dictionary, and then add that as an object in your defaults. Then you only have to set/get once.
If you have large amount of data to save use CoreData else you NSUserDefaults to save it.
I suggest you to use PLIST There are mainly three steps to do this.
1) Generate .plist file.
NSError *error1;
BOOL resourcesAlreadyInDocumentsDirectory;
BOOL copied1;
NSFileManager *fileManager = [NSFileManager defaultManager];
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *filePath1 = [documentsDirectory stringByAppendingString:#"/epub.plist"];
resourcesAlreadyInDocumentsDirectory = [fileManager fileExistsAtPath:filePath1];
if(resourcesAlreadyInDocumentsDirectory == YES) {
} else {
NSString *path1 = [[[NSBundle mainBundle] resourcePath] stringByAppendingFormat:#"/epub.plist"];
copied1 = [fileManager copyItemAtPath:path1 toPath:filePath1 error:&error1];
if (!copied1) {
NSAssert1(0, #"Failed to copy epub.plist. Error %#", [error1 localizedDescription]);
}
}
2) Try to read(open) it.
NSMutableDictionary* dict = [[NSMutableDictionary alloc] initWithContentsOfFile:filePath1];
3) write data to plist file.
[dict setObject:[NSNumber numberWithInt:value] forKey:#"value"];
[dict writeToFile:path atomically:YES];
This is a simple way to use it. I suggest to use .plist file in place of NSUserDefaults.
I'm building an application that allows the user to take several pictures in a row with the device camera.
Every time a picture is taken, it is sent to an array as an NSData variable. The problem is: when the array gets like 30 pictures, it starts to create memory warnings and eventually crashes the application.
When I leave that view I save that array to NSUserDefaults, which can also lead to memory warnings and crashing.
I need to be able to save information of like 200 taken pictures. How can I achieve this without memory warnings?
Btw: I'm using the Apple's SquareCam sample code to take pictures with the camera.
Thanks in advance.
If you don't scale/save as jpg, a photo could be quite big. A solution would be to save it on "disk" in sandbox immediately (with jpeg format would be a good idea anyway) and store in your array only the path of the file you saved.
See a sample code:
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString* imgName = [NSString stringWithFormat:#"%#.jpg", self.uid];
NSString *imagePath = [documentsDirectory stringByAppendingPathComponent:imgName];
NSData *webData = UIImageJPEGRepresentation(self.theImage, 0.5);
[webData writeToFile:imagePath atomically:YES];
self.imageURL = imagePath;
Please don't save image just save only path of image.so, u can better manage them and better for your app. performance.
Right now I have an app that successfully parses JSON from my website. So whenever there is no internet connection, my app crashes. Now I am trying to make it so that when the app is loaded with no internet connection, it will show the data that was shown previously. What would be the best way to do this?
I read this article but I don't know how to embed a JSON file into my app bundle. Could someone explain how to do this?
Thanks in advance!
The best way is:
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *path = [documentsDirectory stringByAppendingPathComponent:#"YourParsedJSON.plist"];
NSFileManager *fileManager = [NSFileManager defaultManager];
if (noInternet){
if ([fileManager fileExistsAtPath: path]){
// if this is true, you have a saved version of your JSON
YourArray = [[NSMutableArray alloc] initWithContentsOfFile: path];
// or
YourDict = [[NSMutableArray alloc] initWithContentsOfFile: path];
}
else{
// first time the app is running, and no internet, no json, inform user about this
}
}
else{
// make an array or dictionary ( what is your JSON )
// response can be a NSDictionary or NSArray
// YourArray = parsedJSON or YourDict = parsedJSON
[YourArray writeToFile:path atomically:YES];
//or
[YourDictionary writeToFile:path atomically:YES];
}
I hope it helps !
Use Apple Reachability sample code to check if your app is able to establish connection to your server.
On first successful request-response, parse the JSON and cache it to disk as a .plist file. This will save you parsing the stored response again. A parsed JSON response can be a NSDictionary or NSArray. Use the writeToFile:atomically: API to write it to disk.
On subsequent request, if reachability fails, i.e. no network connectivity, read the cached response from disk. You need to decide the cache duration and update the plist when a fresh response is fetched.
Hope that helps!
EDIT:
I think I did not understand the question completely. Thanks Xman, for pointing it out. What I would have done in this case is - save the last loaded JSON file to my bundle and use it for displaying information while querying the server and loading updates in the background.
The flow should be like this:
Parse and display data using local JSON file. (Assuming there is local copy of JSON file)
Query the server for latest data.
Upon receiving response, update the bundle with the latest JSON file.
Then, do step 1. In case there is no JSON file, just start from step 2. If there is a Network error display the appropriate information.
This SO question answers how to handle Network connections in iOS: How to check for an active Internet connection on iOS or OSX?
Saving file locally:
Assuming you have the unparsed JSON data in a NSString (responseString) do the following:
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *filePath = [NSString stringWithFormat:#"%#/%#", documentsDirectory, #"latest_json.json"];
NSError *error;
[jsonString_ writeToFile:filePath atomically:YES encoding:NSUTF8StringEncoding error:&error];
NSLog(#"%#", error)
Reading file
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *filePath = [NSString stringWithFormat:#"%#/%#", documentsDirectory, #"latest_json.json"];
NSString *jsonString_ = [NSString stringWithContentsOfFile:filePath encoding:NSUTF8StringEncoding error:&error];
Previous Answer
Embedding JSON file is similar to embedding any resource into your project. The following method shows you how I added an XML file and accessed it in my app.
Drag and drop your JSON/XML file to your resources group/folder in your XCode window. If you don't have the Resouces folder, it is better you create it. Then in your code do this:
NSString* filePath_ = [[NSBundle mainBundle] pathForResource:#"fileName" ofType:#"json"];
NSString *jsonString = [[NSString alloc] initWithContentsOfFile:filePath encoding:NSUTF8StringEncoding error: NULL];
the variable jsonstring contails the JSON information. It is upto you how you would like to parse it.
Which is the best way to store the downloaded images? From there I should be able to use them anywhere in my application, and images should not be deleted at any case (like low space). Any help please.
As per the standard, App related files(Data) need to be stored in document directory only. Once image get download store that images in document directory and maintain unique name for image identification.
-(NSString *)writeDataAsFile:(NSData *)imageData
{
NSArray * paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString * documentsDirectory = [paths objectAtIndex:0];
NSString * thumbNailFilename = [NSString stringWithFormat:#"%#.png",[self GetUUID]]; // Create unique iD
NSString * thumbNailAppFile = [documentsDirectory stringByAppendingPathComponent:thumbNailFilename];
if ([imageData writeToFile:thumbNailAppFile atomically:YES])
{
return thumbNailFilename;
}
return nil;
}
use this method to store the image(downloaded NSData) in document directory.
Retrieve image from the document directory like this
UIImage *thumbnailHomeImage = [UIImage imageWithContentsOfFile:[[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0] stringByAppendingPathComponent:#"%#",imageName]];
take a look at this image caching library. ive used it quite a few times, its really useful
I want to save an image with some metadata changes in a temp folder, without re-encoding the actual image data.
The only method that I found able to do this is ALAssetsLibrary/writeImageDataToSavedPhotosAlbum:metadata:completionBlock:, however, this one saves the image to the Photo Library. Instead, I want to save the image to a temp folder (for instance to share it by email, without populating the Photo Library).
I've tried using CGImageDestinationRef (CGImageDestinationAddImageFromSource), but it can only be created using a decoded image, which means it's re-encoding it when saved (tested, pixel bytes look different).
Are there any other methods/classes available for iOS that can save image data along with metadata, besides using CGImageDestinationRef? Suggestions for workarounds would also be welcomed.
This is a frustrating problem with the iOS SDK. First, I recommend filing an enhancement request.
Now, here is a potential workaround: IF the ALAsset was created by you (i.e., its editable property is YES) then you can basically read the data, write with metadata, read again, save to disk, and then write with the original metadata.
This approach will avoid creating a duplicate image.
Please read the // comments as I skipped some stuff for brevity (like building a metadata dictionary):
ALAsset* asset; //get your asset, don't use this empty one
if (asset.editable) {
// get the source data
ALAssetRepresentation *rep = [asset defaultRepresentation];
Byte *buffer = (Byte*)malloc(rep.size);
// add error checking here
NSUInteger buffered = [rep getBytes:buffer fromOffset:0.0 length:rep.size error:nil];
NSData *sourceData = [NSData dataWithBytesNoCopy:buffer length:buffered freeWhenDone:YES];
// make your metadata whatever you want
// you should use actual metadata, not a blank dictionary
NSDictionary *metadataDictionary = [NSDictionary dictionary];
// these are __weak to avoid creating an ARC retain cycle
NSData __weak *originalData = sourceData;
NSDictionary __weak *originalMetadata = [rep metadata];
[asset setImageData:sourceData
metadata:metadataDictionary
completionBlock:^(NSURL *assetURL, NSError *error) {
//now get your data and write it to file
if (!error) {
//get your data...
NSString *assetPath = [assetURL path];
NSData *targetData = [[NSFileManager defaultManager] contentsAtPath:assetPath];
//...write to file...
NSArray *searchPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentPath = [searchPaths lastObject];
NSURL *fileURL = [NSURL fileURLWithPath:documentPath];
[targetData writeToURL:fileURL atomically:YES];
//...and put it back the way it was
[asset setImageData:originalData metadata:originalMetadata completionBlock:nil];
} else {
// handle error on setting data
NSLog(#"ERROR: %#", [error localizedDescription]);
}
}];
} else {
// you'll need to make a new ALAsset which you have permission to edit and then try again
}
As you can see, if the ALAsset isn't owned by you, you will need to create one, which will add a photo to the user's library, which is exactly what you wanted to avoid. However, as you may have guessed, you cannot delete an ALAsset from the user's photo library, even if your app created it. (Feel free to file another enhancement request for that.)
So, if the photo/image was created in your app, this will work for you.
But if not, it will create an additional copy the user must delete.
The only alternative is to parse the NSData yourself, which would be a pain. There is no open-source library that I am aware of to fill this gap in the iOS SDK.
Alongside iphone-exif, and Aaron's answer, you might also want to look at the libexif c library.
see also HCO23's answer to
How to write or modify EXIF data for an existing image on the filesystem, without loading the image?
(#HCO23 has used libexif in iOS projects).
It's also worth noting that many of the 'professional' metadata editing apps in the app store seem to skirt around the issue by creating sidecar/xmp files.
Try This :
- (void)saveImage: (UIImage*)image
{
if (image != nil)
{
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,
NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString* path = [documentsDirectory stringByAppendingPathComponent:
#"test.png" ];
NSData* data = UIImagePNGRepresentation(image);
[data writeToFile:path atomically:YES];
}
}
- (UIImage*)loadImage
{
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,
NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString* path = [documentsDirectory stringByAppendingPathComponent:
#"test.png" ];
UIImage* image = [UIImage imageWithContentsOfFile:path];
[self sendAction:path];
return image;
}