#interface Entity ()
#property (assign) int searchTotalPagesAll;
#property (assign) int searchTotalPagesIdeas;
#end
#implementation Entity
+ (NSDictionary *)JSONKeyPathsByPropertyKey {
return #{
#"Id": #"entity.id_entity",
#"name": #"entity.name",
#"coverage" : #"entity.coverage",
#"id_city": #"entity.Id_City",
#"cityName":#"entity.city",
#"countryName":#"entity.country",
#"stateName":#"entity.district",
#"countryCode": #"entity.countrycode",
#"keyword1": #"entity.key1",
... etc
Since mantle examples doesn't have a init method, where should I initialize those properties (searchTotalPagesAll, searchTotalPagesIdeas) for default values ? This model has internal methods that need this and several other properties.
Whether you create a Mantle model from JSON or otherwise, the model is initialised with [-initWithDictionary:error:]. In your model class, you can add your defaults to the values used to initialise the model:
- (instancetype)initWithDictionary:(NSDictionary *)dictionaryValue error:(NSError *__autoreleasing *)error {
NSDictionary *defaults = #{
#"searchTotalPagesAll" : #(10),
#"searchTotalPagesIdeas" : #(5)
};
dictionaryValue = [defaults mtl_dictionaryByAddingEntriesFromDictionary:dictionaryValue];
return [super initWithDictionary:dictionaryValue error:error];
}
You can set the default value in init method.
- (instancetype)init
{
self = [super init];
if (self) {
self.searchTotalPagesAll = 1;
self.searchTotalPagesIdeas = 2;
}
return self;
}
Related
I know one way to share data is segue. But in my application I have multiple tabs which contain number of VCs. For instance userName and address. I want to show in some of the VCs these infos.
Every time I query the cloud is not right way. I am following this answer first part: answer. But as a newbie I am not sure how MyDataModel is defined. Is it a NSObject class? I appreciate if anyone can define this class as example with two NSString fields. And how to access these fields in VC and AppDelegate.
Inside AppDelegate
#interface MyAppDelegate : NSObject <UIApplicationDelegate, UITabBarControllerDelegate>
{
MyDataModel *model;
AViewController *aViewController;
BViewController *bViewController;
...
}
#property (retain) IBOutlet AViewController *aViewController;
#property (retain) IBOutlet BViewController *aViewController;
#end
#implementation MyAppDelegate
...
- (void)applicationDidFinishLaunching:(UIApplication *)application
{
...
aViewController.model = model;
bViewController.model = model;
[window addSubview:tabBarController.view];
[window makeKeyAndVisible];
}
Inside VC:
#interface AViewController : UIViewController {
MyDataModel *model;
}
#property (nonatomic, retain) MyDataModel *model;
#end
#interface BViewController : UIViewController {
MyDataModel *model;
}
#property (nonatomic, retain) MyDataModel *model;
#end
The only thing I need is where to define MyDataMode and how to access its fields?
You can use singleton class for that,
----------
SharedManages.h
----------
#import <Foundation/Foundation.h>
#import "Reachability.h"
#import "Reachability.h"
#interface SharedManager : NSObject
{
}
+(SharedManager *)sharedInstance;
// Create property of your object which you want to access from whole over project.
#property (retain, nonatomic) User *loginUser;
#property (assign, readwrite) BOOL isNetAvailable;
#end
----------
----------
SharedManages.m
----------
#import "SharedManager.h"
static SharedManager *objSharedManager;
#implementation SharedManager
#synthesize
isNetAvailable = _isNetAvailable,
loginUser = _ loginUser;
+(SharedManager *)sharedInstance
{
if(objSharedManager == nil)
{
objSharedManager = [[SharedManager alloc] init];
objSharedManager. loginUser = [User alloc]] init];
Reachability *r = [Reachability reachabilityForInternetConnection];
NetworkStatus internetStatus = [r currentReachabilityStatus];
// Bool
if(internetStatus == NotReachable)
{
NSLog(#"Internet Disconnected");
objSharedManager.isNetAvailable = NO; // Internet not Connected
}
else if (internetStatus == ReachableViaWiFi)
{
NSLog(#"Connected via WIFI");
objSharedManager.isNetAvailable = YES; // Connected via WIFI
}
else if (internetStatus == ReachableViaWWAN)
{
NSLog(#"Connected via WWAN");
objSharedManager.isNetAvailable = YES; // Connected via WWAN
}
}
return objSharedManager;
}
#end
Access from other Class...
[SharedManager sharedInstance].isNetAvailable ;
[SharedManager sharedInstance].loginUser ;
Hope, This will help you..
I don't have "local" copies of the values. I set them in the delegate and fetch them from there. That way you don't have to hard code it for all UIViewController's in the delegate.
Assigning values is best done on the first view, or with default values. I personally use viewDidLoad for those kind of things. Since it is only called once on the first view once and pertains until the app is terminated.
Then I get the delegate from inside the VC, call the instance and from there the values.
Swift
Inside AppDelegate:
#UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
var window: UIWindow?
var globals : GlobalValueClass?
First VC:
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
let delegate = UIApplication.sharedApplication().delegate as! AppDelegate
delegate.globals = GlobalValueClass()
delegate.globals!.numbers = [1,2,3]
}
}
Other VC's:
class ViewControllerTwo: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
let delegate = UIApplication.sharedApplication().delegate as! AppDelegate
print(delegate.globals!.numbers)
// Do any additional setup after loading the view.
}
}
Objective C ( don't have the full method in obj-c, but easy to find)
MainClass *appDelegate = (MainClass *)[[UIApplication sharedApplication] delegate];
how to get the delegate in obj-c
Easiest way i could think of is using NSUserDefaults. Save your name and address string in NSUserDefaults like
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
[defaults setValue:YourNameString forKey:#"NameString"];
[defaults setValue:YourAddressString forKey:#"AddressString"];
[defaults synchronize];
and access it in any ViewController as
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
NSString *name = [plistContent valueForKey:#"NameString"];
NSString *address= [plistContent valueForKey:#"AddressString"];
Hope this helps.
You can create a class and use it in your tab controller.
#import <Foundation/Foundation.h>
#interface UserModel : NSObject <NSCoding>
#property (nonatomic, strong) NSString *lastName;
#property (nonatomic, strong) NSString *firstName;
+ (instancetype)modelObjectWithDictionary:(NSDictionary *)dict;
- (instancetype)initWithDictionary:(NSDictionary *)dict;
- (NSDictionary *)dictionaryRepresentation;
#end
implementation file
#import "UserModel.h"
NSString *const kUserModelLastName = #"LastName";
NSString *const kUserModelFirstName = #"FirstName";
#interface UserModel ()
- (id)objectOrNilForKey:(id)aKey fromDictionary:(NSDictionary *)dict;
#end
#implementation UserModel
#synthesize lastName = _lastName;
#synthesize firstName = _firstName;
+ (instancetype)modelObjectWithDictionary:(NSDictionary *)dict
{
return [[self alloc] initWithDictionary:dict];
}
- (instancetype)initWithDictionary:(NSDictionary *)dict
{
self = [super init];
// This check serves to make sure that a non-NSDictionary object
// passed into the model class doesn't break the parsing.
if(self && [dict isKindOfClass:[NSDictionary class]]) {
self.lastName = [self objectOrNilForKey:kUserModelLastName fromDictionary:dict];
self.firstName = [self objectOrNilForKey:kUserModelFirstName fromDictionary:dict];
}
return self;
}
- (NSDictionary *)dictionaryRepresentation
{
NSMutableDictionary *mutableDict = [NSMutableDictionary dictionary];
[mutableDict setValue:self.lastName forKey:kUserModelLastName];
[mutableDict setValue:self.firstName forKey:kUserModelFirstName];
return [NSDictionary dictionaryWithDictionary:mutableDict];
}
- (NSString *)description
{
return [NSString stringWithFormat:#"%#", [self dictionaryRepresentation]];
}
#pragma mark - Helper Method
- (id)objectOrNilForKey:(id)aKey fromDictionary:(NSDictionary *)dict
{
id object = [dict objectForKey:aKey];
return [object isEqual:[NSNull null]] ? nil : object;
}
#pragma mark - NSCoding Methods
- (id)initWithCoder:(NSCoder *)aDecoder
{
self = [super init];
self.lastName = [aDecoder decodeObjectForKey:kUserModelLastName];
self.firstName = [aDecoder decodeObjectForKey:kUserModelFirstName];
return self;
}
- (void)encodeWithCoder:(NSCoder *)aCoder
{
[aCoder encodeObject:_lastName forKey:kUserModelLastName];
[aCoder encodeObject:_firstName forKey:kUserModelFirstName];
}
Import this class where you are setting or initializing data or values. and do below code.
NSDictionary *dicUserModel = [[NSDictionary alloc]initWithObjectsAndKeys:#"Moure",#"LastName",#"Jackson",#"FirstName", nil];
UserModel *userModel = [[UserModel alloc]initWithDictionary:dicUserModel];
//NSUserDefault save your class with all property. and you can simply retrieve your UserModel from NSUserDefault.
//Below code save this model into nsuserdefault.
[[NSUserDefaults standardUserDefaults]setObject:[NSKeyedArchiver archivedDataWithRootObject:userModel] forKey:#"UserModel"];
[[NSUserDefaults standardUserDefaults]synchronize];
You can retrieve you class object using below code.
UserModel *savedUserModel = (UserModel *)[NSKeyedUnarchiver unarchiveObjectWithData:[[NSUserDefaults standardUserDefaults]objectForKey:#"UserModel"]];
NSLog(#"%#",savedUserModel.firstName);
NSLog(#"%#",savedUserModel.lastName);
I simplify the code for ask question.
I want to save more class and load class model file.
But now I simplify parameters to one part (lim) in the model(FlightSettingModel.h).
In the FlightSettingModel.h I have set some parameters in here.
FlightSettingModel.h code below:
#import <Foundation/Foundation.h>
#interface FlightSettingModel : NSObject<NSCoding>
// lim property part
#property float limCurrentVal;
#property float limDefaultVal;
#property float limMaxVal;
#property float limMinVal;
// .... other property part
#end
FlightSettingModel.m code below
#import "FlightSettingModel.h"
#interface FlightSettingModel()
{
}
#end
#implementation FlightSettingModel
-(instancetype)init
{
self = [super init];
if(self)
{
self.limDefaultVal = 3.0;
self.limCurrentVal = 4.0;
self.limMaxVal = 10;
self.limMinVal = 0;
// ... other property part value init .....
}
return self;
}
- (void)setFlightSettingToDefaultValue
{
self.limCurrentVal = self.limDefaultVal;
}
- (void) encodeWithCoder: (NSCoder *)encoder
{
[encoder encodeFloat:self.limCurrentVal forKey:#"limCurrentVal"];
}
- (id)initWithCoder:(NSCoder *)decoder {
if((self = [super init])) {
self.limCurrentVal = [decoder decodeFloatForKey:#"limCurrentVal"];
}
return self;
}
#end
Then I have set the singleton SettingData file to initial the FlightSettingModel and other model class.
The SettingData model header like below:
#import <Foundation/Foundation.h>
#import "FlightSettingModel.h"
#interface SettingData : NSObject
#property (nonatomic,strong) FlightSettingModel *flightSettingModel;
+(SettingData*) sharedInstance;
#end
SettingData.m code below:
#import "SettingData.h"
#implementation SettingData
SettingData *sharedInstance;
+(SettingData*) sharedInstance{
if( sharedInstance == nil )
{
sharedInstance = [SettingData new];
}
return sharedInstance;
}
-(id) init{
self = [super init];
if( self )
{
self.flightSettingModel = [FlightSettingModel new];
}
return self;
}
#end
In my storyboard (UI) is like below:
When I click the save button , I want to save the custom class model(FlightSettingModel.h) in the NSKeyedArchiver. When I click the load, I want to load the model from the archiver using NSKeyedUnarchiver and resetting to the slider.
But now,when I drag the slider to other value(ex:10), then I click the save, then I close the app restart the app. I click the load, the slider value will become 0.
I don't know why when I load the value the all value will become 0;
My view controller code .m below:
#import "ViewController.h"
#import "SettingData.h"
#interface ViewController ()
{
NSString *path;
NSString *fileName;
}
#end
#implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
// file manage
path =[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask, YES) objectAtIndex:0];
fileName = [path stringByAppendingPathComponent:#"flightFile"];
[self setUIValue];
NSLog(#"---");
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
}
- (IBAction)saveAction:(UIButton *)sender {
[NSKeyedArchiver archiveRootObject:[SettingData sharedInstance].flightSettingModel toFile:fileName];
}
- (IBAction)loadAction:(UIButton *)sender {
[SettingData sharedInstance].flightSettingModel = (FlightSettingModel*) [NSKeyedUnarchiver unarchiveObjectWithFile: fileName];
[self setUIValue];
NSLog(#"current Value:%.f",[SettingData sharedInstance].flightSettingModel.limCurrentVal);
}
- (IBAction)sliderChangedAction:(UISlider *)sender {
[SettingData sharedInstance].flightSettingModel.limCurrentVal = sender.value;
self.theTextField.text = [NSString stringWithFormat:#"%.f",self.theSlider.value];
}
-(void) setUIValue
{
// setting slider property
self.theSlider.maximumValue = [SettingData sharedInstance].flightSettingModel.limMaxVal;
self.theSlider.minimumValue = [SettingData sharedInstance].flightSettingModel.limMinVal;
self.theSlider.value = [SettingData sharedInstance].flightSettingModel.limCurrentVal;
self.theTextField.text = [NSString stringWithFormat:#"%.f",self.theSlider.value];
}
#end
Have anyone know where my problem in my code?
thank you very much.
If you want to download the complete code(the question code) , I have upload in github
This behavior happens because the [SettingData sharedInstance].flightSettingModel.limMaxVal and the [SettingData sharedInstance].flightSettingModel.limMinVal are zero:
-(void) setUIValue
{
// setting slider property
self.theSlider.maximumValue = [SettingData sharedInstance].flightSettingModel.limMaxVal;
// self.theSlider.maximumValue = 0
self.theSlider.minimumValue = [SettingData sharedInstance].flightSettingModel.limMinVal;
// self.theSlider.minimumValue = 0
self.theSlider.value = [SettingData sharedInstance].flightSettingModel.limCurrentVal;
// [SettingData sharedInstance].flightSettingModel.limCurrentVal = 10
self.theTextField.text = [NSString stringWithFormat:#"%.f",self.theSlider.value];
}
EDIT: You can fix it by adding this:
- (void) encodeWithCoder: (NSCoder *)encoder {
[encoder encodeFloat:self.limCurrentVal forKey:#"limCurrentVal"];
[encoder encodeFloat:self.limMaxVal forKey:#"limMaxVal"];
[encoder encodeFloat:self.limMinVal forKey:#"limMinVal"];
}
- (id)initWithCoder:(NSCoder *)decoder {
if((self = [super init])) {
self.limCurrentVal = [decoder decodeFloatForKey:#"limCurrentVal"];
self.limMaxVal = [decoder decodeFloatForKey:#"limMaxVal"];
self.limMinVal = [decoder decodeFloatForKey:#"limMinVal"];
}
return self;
}
I have an Objective-C class which looks like this:
#interface CustomObjectHavingData : NSObject
#property (nonatomic, strong) NSData *objWithData;
- (instancetype)initWithObjHavingData;
#end
and implementation like this
#implementation CustomObjectHavingData
- (instancetype)initWithObjHavingData{
if (self = [super init]) {
NSString *str = #"This is simple string.";
self.objWithData = [str dataUsingEncoding:NSUTF8StringEncoding];
}
return self;
}
#end
Now I want to call this initWithObjHavingData in Swift
var objData = CustomObjectHavingData()
This returns nil to me. Please help how I can call the above init method here.
You are not supposed to write initializer like that in Objective C. Either you should have it just init or then if you are passing argument in constructor then only you can name it otherwise.
Here is how you can do it,
#interface CustomObjectHavingData : NSObject
#property (nonatomic, strong) NSData *objWithData;
- (instancetype)initWithObjHavingData:(NSData *)data;
#end
#implementation CustomObjectHavingData
- (instancetype)initWithObjHavingData:(NSData *)data
{
if (self = [super init]) {
_objWithData = data;
}
return self;
}
#end
In Swift, you can simply call it like this,
let myCustomObject = CustomObjectHavingData(objHavingData: someData)
The name is quite inappropriate though.
If you want to call the init method without any parameter with the requirements I posted in the question, we have to write the init method like this:
#interface CustomObjectHavingData : NSObject
#property (nonatomic, strong) NSData *objWithData;
- (id)init;
#end
And implement it like this
#implementation CustomObjectHavingData
- (instancetype)initWithObjHavingData{
if (self = [super init]) {
NSString *str = #"This is simple string.";
self.objWithData = [str dataUsingEncoding:NSUTF8StringEncoding];
}
return self;
}
#end
#implementation CustomObjectHavingData
- (instancetype)initWithObjHavingData:(NSData *)data
{
if (self = [super init]) {
_objWithData = data;
}
return self;
}
#end
Then, you can call this from swift like this:
var objData = CustomObjectHavingData()
It will by default initialize all the objects.
You can use this :
+ (Common *)sharedInstance
{
static Common *sharedInstance_ = nil;
static dispatch_once_t pred;
dispatch_once(&pred, ^{
sharedInstance_ = [[Common alloc] init];
});
return sharedInstance_;
}
After that for calling
var com_obj : Common!
com_obj = Common.sharedInstance()
com_obj.anyfunc(..)
I need to take information submitted by a user, store that information in an NSMutableDictionary, then store that NSMutableDictionary inside another NSMutableDictionary which is then encoded inside another class. For whatever reason, I can't seem to store the first NSMutableDictionary inside of the other.
I had to slim down the code that's in here due to work rules, so sorry if it seems to be missing anything. I only posted the parts that I'm having trouble with.
UserInfo.h:
#import <Foundation/Foundation.h>
#interface MyPlanInfo : NSObject <NSCoding>
#property (nonatomic, strong) NSMutableDictionary *emergencyDictionary;
#end
UserInfo.m:
#import <Foundation/Foundation.h>
#import "MyPlanInfo.h"
static NSString *emergencyDictionaryKey = #"emergencyDictionaryKey";
#implementation MyPlanInfo
#synthesize emergencyDictionary;
- (id) initWithCoder:(NSCoder *)coder
{
self = [super init];
self.emergencyDictionary = [coder decodeObjectForKey:emergencyDictionaryKey];
return self;
}
- (void)encodeWithCoder:(NSCoder *)coder
{
[coder encodeObject:self.emergencyDictionary forKey:emergencyDictionaryKey];
}
#end
infoView.h
#import <UIKit/UIKit.h>
#import "MyPlanInfo.h"
#interface infoView : UIViewController <NSCoding>
{
NSMutableDictionary *emergencyContactInfo;
NSArray *userInfo;
NSArray *userKeys;
NSMutableArray *tempArray;
}
#property (nonatomic, strong) MyPlanInfo *myPlanInfoObject;
-(void)saveUserInfo;
-(void)loadUserInfo;
#end
infoView.m:
#import "infoView.h"
#interface infoView ()
#end
#implementation infoView
static NSString *userInfoKey = #"userInfoKey";
static NSString *userName;
-(void)viewDidLoad
{
[super viewDidLoad];
if(!self.myPlanInfoObject)
{
self.myPlanInfoObject = [[MyPlanInfo alloc] init];
}
[self loadUserInfo];
}
-(void)addToDictionary
{
emergencyContactInfo = [NSMutableDictionary dictionaryWithObjects:userInfo forKeys:userKeys];
if([userInfo count] != 0 || userInfo == nil)
{
self.myPlanInfoObject.emergencyDictionary = [NSMutableDictionary dictionaryWithObject:emergencyContactInfo forKey:userName];
}
[self saveUserInfo];
}
- (void)saveUserInfo
{
NSData *userInfoData = [NSKeyedArchiver archivedDataWithRootObject:self.myPlanInfoObject];
[[NSUserDefaults standardUserDefaults] setObject:userInfoData forKey:userInfoKey];
}
- (void)loadUserInfo
{
NSData *userInfoData = [[NSUserDefaults standardUserDefaults] objectForKey:userInfoKey];
if(userInfoData)
{
self.myPlanInfoObject = [NSKeyedUnarchiver unarchiveObjectWithData:userInfoData];
}
}
#end
In infoView.m, in the addToDictionary method, userInfo is an array of user inputted information, and userKey's is an array of key's. The emergencyContactInfo NSMutableDictionary works just fine, everything is in it, but when I try to set that as an object in a new NSMutableDictionary, for a key, it doesn't work. Everything is nil.
Anyone have any ideas on how what I'm doing wrong?
Edit: If you down vote, please leave a reason as to why so that I can avoid doing whatever I did wrong in the future.
In the following line you’re creating an instance of MyPlanInfo using plain alloc/init:
self.myPlanInfoObject = [[MyPlanInfo alloc] init];
However, at least in the code provided, you haven’t overridden init in MyPlanInfo, but instead, initWithCoder::
- (id) initWithCoder:(NSCoder *)coder
{
self = [super init];
self.emergencyDictionary = [coder decodeObjectForKey:emergencyDictionaryKey];
return self;
}
When you use just plain init, the MyPlanInfo’s emergencyDictionary instance variable will be nil. You should likely add something like the following to MyPlanInfo to override init:
- (id) init
{
if ((self = [super init])) {
emergencyDictionary = [[NSMutableDictionary alloc] init];
}
return self;
}
That will assure that the newly created MyPlanInfo instance has a proper NSMutableDictionary that can be manipulated from other classes.
I'm using NSValueTranformer to encrypt certain Core Data attributes. This all works fine, except I need to be able to use a different encryption key depending on the NSManagedObject. Is there anyway I can access this entity from within my transformer class?
The use case is I have multiple users with different passwords that can access different NSManagedObject entities. If I use the same encryption key for all of the objects, someone could just reassign who owns them in the SQL db and they would still decrypt.
Any ideas on the best way to go about this?
Edit:
I should mention I'm doing this in iOS.
Third times the charm? Let me see if I can address your only-transform-when-going-to-disk requirement. Think of this as a hybrid of the other two approaches.
#interface UserSession : NSObject
+ (UserSession*)currentSession;
+ (void)setCurrentSession: (UserSession*)session;
- (id)initWithUserName: (NSString*)username andEncryptionKey: (NSData*)key;
#property (nonatomic, readonly) NSString* userName;
#property (nonatomic, readonly) NSData* encryptionKey;
#end
#implementation UserSession
static UserSession* gCurrentSession = nil;
+ (UserSession*)currentSession
{
#synchronized(self)
{
return gCurrentSession;
}
}
+ (void)setCurrentSession: (UserSession*)userSession
{
#synchronized(self)
{
gCurrentSession = userSession;
}
}
- (id)initWithUserName: (NSString*)username andEncryptionKey: (NSData*)key
{
if (self = [super init])
{
_userName = [username copy];
_encryptionKey = [key copy];
}
return self;
}
- (void)dealloc
{
_userName = nil;
_encryptionKey = nil;
}
#end
#interface EncryptingValueTransformer : NSValueTransformer
#end
#implementation EncryptingValueTransformer
- (id)transformedValue:(id)value
{
UserSession* session = [UserSession currentSession];
NSAssert(session, #"No user session! Can't decrypt!");
NSData* key = session.encryptionKey;
NSData* decryptedData = Decrypt(value, key);
return decryptedData;
}
- (id)reverseTransformedValue:(id)value
{
UserSession* session = [UserSession currentSession];
NSAssert(session, #"No user session! Can't encrypt!");
NSData* key = session.encryptionKey;
NSData* encryptedData = Encrypt(value, key);
return encryptedData;
}
#end
The only tricky part here is that you have to be sure that the current UserSession is set up before you create the managed object context and isn't changed until after the context is saved and deallocated.
Hope this helps.
You can create custom instances of NSValueTransformer subclasses that have state (i.e. the encryption key) and pass them in to -bind:toObject:withKeyPath:options: in the options dictionary using the NSValueTransformerBindingOption key.
You won't be able to set this up in IB directly since IB references value transformers by class name, but you can do it in code. If you're feeling extra ambitious you can set up the bindings in IB and then replace them with different options in code later.
It might look something like this:
#interface EncryptingValueTransformer : NSValueTransformer
#property (nonatomic,readwrite,copy) NSData* encryptionKey;
#end
#implementation EncryptingValueTransformer
- (void)dealloc
{
_encryptionKey = nil;
}
- (id)transformedValue:(id)value
{
if (!self.encryptionKey)
return nil;
// do the transformation
return value;
}
- (id)reverseTransformedValue:(id)value
{
if (!self.encryptionKey)
return nil;
// Do the reverse transformation
return value;
}
#end
#interface MyViewController : NSViewController
#property (nonatomic, readwrite, assign) IBOutlet NSControl* controlBoundToEncryptedValue;
#end
#implementation MyViewController
// Other stuff...
- (void)loadView
{
[super loadView];
// Replace IB's value tansformer binding settings (which will be by class and not instance) with specific,
// stateful instances.
for (NSString* binding in [self.controlBoundToEncryptedValue exposedBindings])
{
NSDictionary* bindingInfo = [self.controlBoundToEncryptedValue infoForBinding: binding];
NSDictionary* options = bindingInfo[NSOptionsKey];
if ([options[NSValueTransformerNameBindingOption] isEqual: NSStringFromClass([EncryptingValueTransformer class])])
{
// Out with the old
[self.controlBoundToEncryptedValue unbind: binding];
// In with the new
NSMutableDictionary* mutableOptions = [options mutableCopy];
mutableOptions[NSValueTransformerNameBindingOption] = nil;
mutableOptions[NSValueTransformerBindingOption] = [[EncryptingValueTransformer alloc] init];
[self.controlBoundToEncryptedValue bind: binding
toObject: bindingInfo[NSObservedObjectKey]
withKeyPath: bindingInfo[NSObservedKeyPathKey]
options: mutableOptions];
}
}
}
// Assuming you're using the standard representedObject pattern, this will get set every time you want
// your view to expose new model data. This is a good place to update the encryption key in the transformers'
// state...
- (void)setRepresentedObject:(id)representedObject
{
for (NSString* binding in [self.controlBoundToEncryptedValue exposedBindings])
{
id transformer = [self.controlBoundToEncryptedValue infoForBinding: NSValueBinding][NSOptionsKey][NSValueTransformerBindingOption];
EncryptingValueTransformer* encryptingTransformer = [transformer isKindOfClass: [EncryptingValueTransformer class]] ? (EncryptingValueTransformer*)transformer : nil;
encryptingTransformer.encryptionKey = nil;
}
[super setRepresentedObject:representedObject];
// Get key from model however...
NSData* encryptionKeySpecificToThisUser = /* Whatever it is... */ nil;
for (NSString* binding in [self.controlBoundToEncryptedValue exposedBindings])
{
id transformer = [self.controlBoundToEncryptedValue infoForBinding: NSValueBinding][NSOptionsKey][NSValueTransformerBindingOption];
EncryptingValueTransformer* encryptingTransformer = [transformer isKindOfClass: [EncryptingValueTransformer class]] ? (EncryptingValueTransformer*)transformer : nil;
encryptingTransformer.encryptionKey = encryptionKeySpecificToThisUser;
}
}
// ...Other stuff
#end
OK. This was bugging me so I thought about it some more... I think the easiest way is to have some sort of "session" object and then have a "derived property" on your managed object. Assuming you have an entity called UserData with a property called encryptedData, I whipped up some code that might help illustrate:
#interface UserData : NSManagedObject
#property (nonatomic, retain) NSData * unencryptedData;
#end
#interface UserData () // Private
#property (nonatomic, retain) NSData * encryptedData;
#end
// These functions defined elsewhere
NSData* Encrypt(NSData* clearData, NSData* key);
NSData* Decrypt(NSData* cipherData, NSData* key);
#interface UserSession : NSObject
+ (UserSession*)currentSession;
- (id)initWithUserName: (NSString*)username andEncryptionKey: (NSData*)key;
#property (nonatomic, readonly) NSString* userName;
#property (nonatomic, readonly) NSData* encryptionKey;
#end
#implementation UserData
#dynamic encryptedData;
#dynamic unencryptedData;
+ (NSSet*)keyPathsForValuesAffectingUnencryptedData
{
return [NSSet setWithObject: NSStringFromSelector(#selector(encryptedData))];
}
- (NSData*)unencryptedData
{
UserSession* session = [UserSession currentSession];
if (nil == session)
return nil;
NSData* key = session.encryptionKey;
NSData* encryptedData = self.encryptedData;
NSData* decryptedData = Decrypt(encryptedData, key);
return decryptedData;
}
- (void)setUnencryptedData:(NSData *)unencryptedData
{
UserSession* session = [UserSession currentSession];
NSAssert(session, #"No user session! Can't encrypt!");
NSData* key = session.encryptionKey;
NSData* encryptedData = Encrypt(unencryptedData, key);
self.encryptedData = encryptedData;
}
#end
#implementation UserSession
static UserSession* gCurrentSession = nil;
+ (UserSession*)currentSession
{
#synchronized(self)
{
return gCurrentSession;
}
}
+ (void)setCurrentSession: (UserSession*)userSession
{
#synchronized(self)
{
gCurrentSession = userSession;
}
}
- (id)initWithUserName: (NSString*)username andEncryptionKey: (NSData*)key
{
if (self = [super init])
{
_userName = [username copy];
_encryptionKey = [key copy];
}
return self;
}
-(void)dealloc
{
_userName = nil;
_encryptionKey = nil;
}
#end
The idea here is that when a given user logs in you create a new UserSession object and call +[UserSession setCurrentSession: [[UserSession alloc] initWithUserName: #"foo" andEncryptionKey: <whatever>]]. The derived property (unencryptedData) accessor and mutator get the current session and use the key to transform the values back and forth to the "real" property. (Also, don't skip over the +keyPathsForValuesAffectingUnencryptedData method. This tells the runtime about the relationship between the two properties, and will help things work more seamlessly.)