We are using Alamofire 4 and want to match URLSessionTasks to entities in a database.
We first used the taskDescription field of URLSessionTask to put UUID of a database entity there, but then figured out that Alamofire creates a new task on request retry and this field is not copied over. taskIdentifier also changes with every new task created, and there seem to be no way to track the change of taskIdentifier in Alamofire.
Are there any other techniques to match tasks and entities in a database or files? The end goal is to delete file + entity if background upload request succeeds. And that might happen after the app has been terminated, thus we currently store information in a database.
Assuming AlamoFire isn't doing something nutty, you should be able to do something like this:
NSString *const identifierProperty = #"com.you.yourProduct.requestID";
NSString *myIdentifier = [NSUUID UUID].UUIDString;
[NSURLProtocol setProperty:myIdentifier
inKey:identifierProperty
inRequest:theURLRequest];
and then, later, to get it back:
NSString *requestID = [NSURLProtocol propertyForKey:identifierProperty
inRequest:theURLRequest];
Apologies for the Objective-C, but it should be easily convertible to Swift.
Once you do that, the property should be copied whenever the request is copied, just like any first-class property on the request. You might even consider creating a category on NSURLRequest to expose the underlying value as an actual native property.
Related
I'm a nwebie in Core Data, i have designed a navigation based application and some of the data i use are created on run time(come from a URL via JSON). I took a few tutorials an searched for almost a day but haven't still realized how to save the incoming JSON data to the Entity (or event?) in my Core Data model. I fetch the data in the DetailViewController class and i need to save this data to Core Data(I have prepared an Entity with 7 properties). Can anyone please help?(If you know a good tutorial or sample code i will be pleased)
EDIT This may be a little specific but i really have trouble with and need just a little help.
My data comes to the app from a kind of restful server(i wrote it in PHP), firstly user enters his/her login informations(which i have saved to the database on server before) and when the response data comes i will use different elements of it in differen views(for example the user_id will be used on a view and the buttonData etc on other views). My question is, how will i save JSON data into my core data model(has tree Entities for the moment). Thanks in advance
Note: I lokked arround a lot but couldn't find any answer&tutorial about an app like mine
The best way to do that would be to create entities corresponding to JSON structure. Easiest was is when each JSON object becomes an entity, and arrays become arrays of entities. Be reasonable, however, and don't introduce too much overkill for JSON subobjects that are essentially part of its superobject.
When you have created entities, you can start off with the parsing and translation. Use some JSON framework (starting from iOS5 there's one from Apple) and parse JSON string into object tree, where root item is either an NSArray or NSDictionary, and subelements will be NSArray, NSDictionary, NSNumber, NSString or NSNull.
Go over them one by one in iterational loops and assign according values to your core data entity attributes. You can make use of NSKeyValueCoding here and avoid too much manual mapping of the attribute names. If your JSON attributes are of the same name as entity attributes, you'll be able to just go over all dictionary elements and parse them into attributes of the same name.
Example
My parsing code in the similar situation was as follows:
NSDictionary *parsedFeed = /* your way to get a dictionary */;
for (NSString *key in parsedFeed) {
id value = [parsedFeed objectForKey:key];
// Don't assign NSNull, it will break assignments to NSString, etc.
if (value && [value isKindOfClass:[NSNull class]])
value = nil;
#try {
[yourCreatedEntity setValue:value forKey:property];
} #catch (NSException *exception) {
// Exception means such attribute is not defined in the class or some other error.
}
}
This code will work in trivial situation, however, it may need to be expanded, depending on your needs:
With some kinds of custom mappings in case you want your JSON value be placed in differently named attribute.
If your JSON has sub-objects or arrays of sub-objects, you will need to detect those cases, for example in setters, and initiate new parsing one level deeper. Otherwise with my example you will face the situation that assigns NSDictionary object to an NSManagedObject.
I don't think it is reasonable to dive into these, more advanced matters in scope of this answer, as it will expand it too much.
I suggest you to use this library : https://github.com/TouchCode/TouchJSON
And then if you want to make a factory to parse json and feed your code data, you can use selectors to call methods to fill all your attributes.
Chances are your JSON data gets converted to an NSDictionary or NSArray (or some combination of the two). Simply extract the key/values from the JSON structure and add them to your entity class.
This lib helps me lot
Features
Attribute and relationship mapping to JSON key paths.
Value transformation using named NSValueTransformer objects.
Object graph preservation.
Support for entity inheritance
Works vice-versa
I have what I believe to be the simplest possible start to using Magical Record. I simply set up the stack and do a findAll call -- which I expect to return an empty array since this is a first run of the application. My code is below. For some reason, what I actually get is
executeFetchRequest:error: A fetch request must have an entity.
I can't for the life of me figure out why. I don't have versions of my data model, or anything really special. Just an entity and a generated NSMangedObject.. Has anyone seen this before?
- (void)applicationDidFinishLaunching:(NSNotification *)aNotification
{
[MagicalRecord setupAutoMigratingCoreDataStack];
// Task *task = [Task MR_createEntity];
// task.title = #"Title";
NSArray *contexts = [Task MR_findAll];
NSLog(#"Initial load found %lu contexts", contexts.count);
}
Did you create and populate an NSManagedObjectModel using Xcode and the Core Data Entity Modeler? The error you're seeing happens when the entity isn't found in the model, or you don't have a model in the first place. Double check your entity name and class names as well. If you aren't using mogenerator, the you will need to make sure they match, or map them yourself using MR_entityName in your own entity's code.
Turns out the latest code in the main branch must have a bug.. I pulled the 2.2 branch instead, and it all started working.. Really odd, but there it is for anyone that stumbles on it.. Make sure you pull the latest stable!
Currently I'm trying to implement support for multiple versions of iTunes via ScriptingBridge.
For example the method signature of the property playerPosition changed from (10.7)
#property NSInteger playerPosition; // the player’s position within the currently playing track in seconds.
to (11.0.5)
#property double playerPosition; // the player’s position within the currently playing track in seconds
With the most current header file in my application and an older iTunes version the return value of this property would always be 3. Same thing goes the other way around.
So I went ahead and created three different iTunes header files, 11.0.5, 10.7 and 10.3.1 via
sdef /path/to/application.app | sdp -fh --basename applicationName
For each version of iTunes I adapted the basename to inlcude the version, e.g. iTunes_11_0_5.h.
This results in the interfaces in the header files to be prefixed with their specific version number.
My goal is/was to typecast the objects I'd use with the interfaces of the correct version.
The path to iTunes is fetched via a NSWorkspace method, then I'm creating a NSBundle from it and extract the CFBundleVersion from the infoDictionary.
The three different versions (11.0.5, 10.7, 10.3.1) are also declared as constants which I compare to the iTunes version of the user via
[kiTunes_11_0_5 compare:versionInstalled options:NSNumericSearch]
Then I check if each result equals NSOrderedSame, so I'll know which version of iTunes the user has installed.
Implementing this with if statement got a bit out of hand, as I'd need to do these typecasts at many different places in my class and I then started to realize that this will result in a lot of duplicate code and tinkered around and thought about this to find a different solution, one that is more "best practice".
Generally speaking, I'd need to dynamically typecast the objects I use, but I simply can't find a solution which wouldn't end in loads of duplicated code.
Edit
if ([kiTunes_11_0_5 compare:_versionString options:NSNumericSearch] == NSOrderedSame) {
NSLog(#"%#, %#", kiTunes_11_0_5, _versionString);
playerPosition = [(iTunes_11_0_5_Application*)_iTunes playerPosition];
duration = [(iTunes_11_0_5_Track*)_currentTrack duration];
finish = [(iTunes_11_0_5_Track*)_currentTrack finish];
} else if [... and so on for each version to test and cast]
[All code directly entered into answer.]
You could tackle this with a category, a proxy, or a helper class, here is a sketch of one possible design for the latter.
First create a helper class which takes and instance of your iTunes object and the version string. Also to avoid doing repeated string comparisons do the comparison once in the class setup. You don't give the type of your iTunes application object so we'll randomly call it ITunesAppObj - replace with the correct type:
typedef enum { kEnumiTunes_11_0_5, ... } XYZiTunesVersion;
#implementation XYZiTunesHelper
{
ITunesAppObj *iTunes;
XYZiTunesVersion version;
}
- (id) initWith:(ITunesAppObj *)_iTunes version:(NSString *)_version
{
self = [super self];
if (self)
{
iTunes = _iTunes;
if ([kiTunes_11_0_5 compare:_version options:NSNumericSearch] == NSOrderedSame)
version = kEnumiTunes_11_0_5;
else ...
}
return self;
}
Now add an item to this class for each item which changes type between versions, declaring it with whatever "common" type you pick. E.g. for playerPosition this might be:
#interface XYZiTunesHelper : NSObject
#property double playerPosition;
...
#end
#implementation XYZiTunesHelper
// implement getter for playerPosition
- (double) playerPosition
{
switch (version)
{
case kEnumiTunes_11_0_5:
return [(iTunes_11_0_5_Application*)_iTunes playerPosition];
// other cases - by using an enum it is both fast and the
// compiler will check you cover all cases
}
}
// now implement the setter...
Do something similar for track type. Your code fragment then becomes:
XYZiTunesHelper *_iTunesHelper = [[XYZiTunesHelper alloc] init:_iTunes
v ersion:_versionString];
...
playerPosition = [_iTunesHelper playerPosition];
duration = [_currentTrackHelper duration];
finish = [_currentTrackHelper finish];
The above is dynamic as you requested - at each call there is a switch to invoke the appropriate version. You could of course make the XYZiTunesHelper class abstract (or an interface or a protocol) and write three implementations of it one for each iTunes version, then you do the test once and select the appropriate implementation. This approach is more "object oriented", but it does mean the various implementations of, say, playerPosition are not together. Pick whichever style you feel most comfortable with in this particular case.
HTH
Generating multiple headers and switching them in and out based on the application's version number is a really bad 'solution': aside from being horribly complicated, it is very brittle since it couples your code to specific iTunes versions.
Apple events, like HTTP, were designed by people who understood how to construct large, flexible long-lived distributed systems whose clients and servers could evolve and change over time without breaking each other. Scripting Bridge, like a lot of the modern 'Web', was not.
...
The correct way to retrieve a specific type of value is to specify your required result type in the 'get' event. AppleScript can do this:
tell app "iTunes" to get player position as real
Ditto objc-appscript, which provides convenience methods specifically for getting results as C numbers:
ITApplication *iTunes = [ITApplication applicationWithBundleID: #"com.apple.itunes"];
NSError *error = nil;
double pos = [[iTunes playerPosition] getDoubleWithError: &error];
or, if you'd rather get the result as an NSNumber:
NSNumber *pos = [[iTunes playerPosition] getWithError: &error];
SB, however, automatically sends the 'get' event for you, giving you no what to tell it what type of result you want before it returns it. So if the application decides to return a different type of value for any reason, SB-based ObjC code breaks from sdp headers onwards.
...
In an ideal world you'd just ditch SB and go use objc-appscript which, unlike SB, knows how to speak Apple events correctly. Unfortunately, appscript is no longer maintained thanks to Apple legacying the original Carbon Apple Event Manager APIs without providing viable Cocoa replacements, so isn't recommended for new projects. So you're pretty much stuck with the Apple-supplied options, neither of which is good or pleasant to use. (And then they wonder why programmers hate everything AppleScript so much...)
One solution would be to use AppleScript via the AppleScript-ObjC bridge. AppleScript may be a lousy language, but at least it knows how to speak Apple events correctly. And ASOC, unlike Cocoa's crappy NSAppleScript class, takes most of the pain out of gluing AS and ObjC code together in your app.
For this particular problem though, it is possible to monkey-patch around SB's defective glues by dropping down to SB's low-level methods and raw four-char codes to construct and send the event yourself. It's a bit tedious to write, but once it's done it's done (at least until the next time something changes...).
Here's a category that shows how to do this for the 'player position' property:
#implementation SBApplication (ITHack)
-(double)iTunes_playerPosition {
// Workaround for SB Fail: older versions of iTunes return typeInteger while newer versions
// return typeIEEE64BitFloatingPoint, but SB is too stupid to handle this correctly itself
// Build a reference to the 'player position' property using four-char codes from iTunes.sdef
SBObject *ref = [self propertyWithCode:'pPos'];
// Build and send the 'get' event to iTunes (note: while it is possible to include a
// keyAERequestedType parameter that tells the Apple Event Manager to coerce the returned
// AEDesc to a specific number type, it's not necessary to do so as sendEvent:id:parameters:
// unpacks all numeric AEDescs as NSNumber, which can perform any needed coercions itself)
NSNumber *res = [self sendEvent:'core' id:'getd' parameters: '----', ref, nil];
// The returned value is an NSNumber containing opaque numeric data, so call the appropriate
// method (-integerValue, -doubleValue, etc.) to get the desired representation
return [res doubleValue];
}
#end
Notice I've prefixed the method name as iTunes_playerPosition. Unlike objc-appscript, which uses static .h+.m glues, SB dynamically creates all of its iTunes-specific glue classes at runtime, so you can't add categories or otherwise patch them directly. All you can do is add your category to the root SBObject/SBApplication class, making them visible across all classes in all application glues. Swizzling the method names should avoid any risk of conflict with any other applications' glue methods, though obviously you still need to take care to call them on the right objects otherwise you'll likely get unexpected results or errors.
Obviously, you'll have to repeat this patch for any other properties that have undergone the same enhancement in iTunes 11, but at least once done you won't have to change it again if, say, Apple revert back to integers in a future release or if you've forgotten to include a previous version in your complicated switch block. Plus, of course, you won't have to mess about generating multiple iTunes headers: just create one for the current version and remember to avoid using the original -playerPosition and other broken SB methods in your code and use your own robust iTunes_... methods instead.
I have an app which shows the user a number of messages. I need to inform the server that the user has read the messages. To do this, I need to send an HTTP POST request to /api/mark_as_read/ with the IDs of the messages to mark as read, like:
ID: 1234
ID: 5678
ID: 90AB
Note that the HTTP spec allows possibly duplicate keys, which the API uses in this case.
I am currently using AFHTTPClient (part of the AFNetworking library). POST parameters are passed into AFHTTPClient as an NSDictionary, which of course has unique keys, meaning I can only pass in one value called "ID".
I've searched for a while for a solution and haven't been able to dig anything up. But I'm sure lots of people have encountered the issue before. How do I pass my HTTP client a dictionary with non-unique keys in Objective-C?
Update - I was able to resolve the issue by updating the AFNetworking library and putting an array of IDs in one NSDictionary value. (See below.)
Try passing an array for values:
NSArray *values = [NSArray arrayWithObjects:#"1234", #"5678", #"90AB", nil];
NSDictionary *params = [NSDictionary dictionaryWithObjectAndKey:values, #"ID"];
a dictionary is a set and keys are unique by 'definition'
no way this can be done with standard dict
BUT one could inherit set and just use keys array and dups array.
afnetwork would use it as a dictionary and it would provide the output you want.
they might have such a class OR you can easily write one kinda similiar
http://cocoaheads.byu.edu/code/CHDataStructures
** this is inefficient and should only be used for THIS purpose **
I'm a nwebie in Core Data, i have designed a navigation based application and some of the data i use are created on run time(come from a URL via JSON). I took a few tutorials an searched for almost a day but haven't still realized how to save the incoming JSON data to the Entity (or event?) in my Core Data model. I fetch the data in the DetailViewController class and i need to save this data to Core Data(I have prepared an Entity with 7 properties). Can anyone please help?(If you know a good tutorial or sample code i will be pleased)
EDIT This may be a little specific but i really have trouble with and need just a little help.
My data comes to the app from a kind of restful server(i wrote it in PHP), firstly user enters his/her login informations(which i have saved to the database on server before) and when the response data comes i will use different elements of it in differen views(for example the user_id will be used on a view and the buttonData etc on other views). My question is, how will i save JSON data into my core data model(has tree Entities for the moment). Thanks in advance
Note: I lokked arround a lot but couldn't find any answer&tutorial about an app like mine
The best way to do that would be to create entities corresponding to JSON structure. Easiest was is when each JSON object becomes an entity, and arrays become arrays of entities. Be reasonable, however, and don't introduce too much overkill for JSON subobjects that are essentially part of its superobject.
When you have created entities, you can start off with the parsing and translation. Use some JSON framework (starting from iOS5 there's one from Apple) and parse JSON string into object tree, where root item is either an NSArray or NSDictionary, and subelements will be NSArray, NSDictionary, NSNumber, NSString or NSNull.
Go over them one by one in iterational loops and assign according values to your core data entity attributes. You can make use of NSKeyValueCoding here and avoid too much manual mapping of the attribute names. If your JSON attributes are of the same name as entity attributes, you'll be able to just go over all dictionary elements and parse them into attributes of the same name.
Example
My parsing code in the similar situation was as follows:
NSDictionary *parsedFeed = /* your way to get a dictionary */;
for (NSString *key in parsedFeed) {
id value = [parsedFeed objectForKey:key];
// Don't assign NSNull, it will break assignments to NSString, etc.
if (value && [value isKindOfClass:[NSNull class]])
value = nil;
#try {
[yourCreatedEntity setValue:value forKey:property];
} #catch (NSException *exception) {
// Exception means such attribute is not defined in the class or some other error.
}
}
This code will work in trivial situation, however, it may need to be expanded, depending on your needs:
With some kinds of custom mappings in case you want your JSON value be placed in differently named attribute.
If your JSON has sub-objects or arrays of sub-objects, you will need to detect those cases, for example in setters, and initiate new parsing one level deeper. Otherwise with my example you will face the situation that assigns NSDictionary object to an NSManagedObject.
I don't think it is reasonable to dive into these, more advanced matters in scope of this answer, as it will expand it too much.
I suggest you to use this library : https://github.com/TouchCode/TouchJSON
And then if you want to make a factory to parse json and feed your code data, you can use selectors to call methods to fill all your attributes.
Chances are your JSON data gets converted to an NSDictionary or NSArray (or some combination of the two). Simply extract the key/values from the JSON structure and add them to your entity class.
This lib helps me lot
Features
Attribute and relationship mapping to JSON key paths.
Value transformation using named NSValueTransformer objects.
Object graph preservation.
Support for entity inheritance
Works vice-versa