I have my own object class from inherited from NSObject
#interface BlockedCell : NSObject
{
NSValue *gridValue;
NSString *name;
}
#property (nonatomic, retain) NSValue *gridValue;
#property (nonatomic, retain) NSString *name;
#end
So I try to create a few objects:
NSMutableDictionary *dict = [[dict alloc] init];
for (int i = 0; i < 5; ++i)
{
BlockedCell *block = [[BlockedCell alloc] init];
block.gridValue = [NSValue valueWithCGPoint: CGPointMake(0.0f, 0.0f)];
block.name = #"something";
[dict setObject: block forKey: [NSString stringWithFormat: #"item_%d", i]];
[block release];
}
if([dict writeToFile: path atomic: YES])
NSLog(#"Saved");
else
NSLog(#"Failed to save");
[dict release];
And what I get for the output is "Failed to save"..
If my dictionary does not contains any data, then it will output "Saved"
EDIT:
After I did more testing, I found out that actually is the NSValue causing the saving failed.
So what should I do if I want to save CGPoint into plist?
As you discovered, property lists cannot store NSValue objects directly. The supported classes are NSData, NSString, NSArray, NSDictionary, NSDate, and NSNumber, as documented in the NSPropertyListSerialization Class Reference.
The easiest workaround would be to use NSString instead of NSValue:
block.gridString = NSStringFromCGPoint(CGPointZero);
CGPoint point = CGPointFromString(block.gridString);
you cant save NSValue directly.In your case you have to save a point in the form ofstring use below line
CGPoint point = CGPointMake(10.0,20.0)
//you need to translate the point into a compatible "Plist" object such as NSString
//luckily, there is a method for that
[rectArray addObject:NSStringFromPoint(point)];
//save into a plist
.....
on retrieval of this value
CGPoint Point = CGPointFromString([rectArray objectAtIndex:0]);
Related
Hello I a class of type NSObject:
ProductDetails *details = [[ProductDetails alloc] init];
details.name = #"Soap1";
details.color = #"Red";
details.quantity = 4;
I want to pass the "details" object to a dictionary.
I did,
NSDictionary *dict = [NSDictionary dictionaryWithObject:details forKey:#"details"];
I am passing this dict to another method which performs a check on JSONSerialization:
if(![NSJSONSerialization isValidJSONObject:dict])
And I am getting a crash on this check. Am I doing anything wrong here? I know that the details I am getting is a JSON object and I am assigning it to the properties in my ProductDetails class.
Please help me. I am a noob in Objective-C.
I now tried:
NSError* error;
NSDictionary* json = [NSJSONSerialization JSONObjectWithData:(NSData*)details options:kNilOptions error:&error];
All I need here is an easy way to convert details to NSData.
I noticed that I have an array inside my object may be thats why all the ways I tried is throwing an exception. However since this question is becoming to big, I have started an another question thread for it where I have displayed the data I am getting inside the object - https://stackoverflow.com/questions/19081104/convert-nsobject-to-nsdictionary
This may well be the easiest way to achieve it. Do import #import <objc/runtime.h> in your class file.
#import <objc/runtime.h>
ProductDetails *details = [[ProductDetails alloc] init];
details.name = #"Soap1";
details.color = #"Red";
details.quantity = 4;
NSDictionary *dict = [self dictionaryWithPropertiesOfObject: details];
NSLog(#"%#", dict);
//Add this utility method in your class.
- (NSDictionary *) dictionaryWithPropertiesOfObject:(id)obj
{
NSMutableDictionary *dict = [NSMutableDictionary dictionary];
unsigned count;
objc_property_t *properties = class_copyPropertyList([obj class], &count);
for (int i = 0; i < count; i++) {
NSString *key = [NSString stringWithUTF8String:property_getName(properties[i])];
[dict setObject:[obj valueForKey:key] forKey:key];
}
free(properties);
return [NSDictionary dictionaryWithDictionary:dict];
}
NSDictionary *details = {#"name":product.name,#"color":product.color,#"quantity":#(product.quantity)};
NSError *error;
NSData *jsonData = [NSJSONSerialization dataWithJSONObject:details
options:NSJSONWritingPrettyPrinted // Pass 0 if you don't care about the readability of the generated string
error:&error];
if (! jsonData) {
NSLog(#"Got an error: %#", error);
} else {
NSString *jsonString = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
}
Second part's source: Generate JSON string from NSDictionary in iOS
As mmackh said, you want to define a custom method for your ProductDetails object that will return a simple NSDictionary of values, e.g.:
#implementation ProductDetails
- (id)jsonObject
{
return #{#"name" : self.name,
#"color" : self.color,
#"quantity" : #(self.quantity)};
}
...
Let's assume that we added manufacturer property to our ProductDetails, which referenced a ManufacturerDetails class. We'd just write a jsonObject for that class, too:
#implementation ManufacturerDetails
- (id)jsonObject
{
return #{#"name" : self.name,
#"address1" : self.address1,
#"address2" : self.address2,
#"city" : self.city,
...
#"phone" : self.phone};
}
...
And then change the jsonObject for ProductDetails to employ that, e.g.:
#implementation ProductDetails
- (id)jsonObject
{
return #{#"name" : self.name,
#"color" : self.color,
#"quantity" : #(self.quantity),
#"manufacturer" : [self.manufacturer jsonObject]};
}
...
If you have potentially nested collection objects (arrays and/or dictionaries) with custom objects that you want to encode, you could write a jsonObject method for each of those, too:
#interface NSDictionary (JsonObject)
- (id)jsonObject;
#end
#implementation NSDictionary (JsonObject)
- (id)jsonObject
{
NSMutableDictionary *dictionary = [NSMutableDictionary dictionary];
[self enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) {
if ([obj respondsToSelector:#selector(jsonObject)])
[dictionary setObject:[obj jsonObject] forKey:key];
else
[dictionary setObject:obj forKey:key];
}];
return [NSDictionary dictionaryWithDictionary:dictionary];
}
#end
#interface NSArray (JsonObject)
- (id)jsonObject;
#end
#implementation NSArray (JsonObject)
- (id)jsonObject
{
NSMutableArray *array = [NSMutableArray array];
[self enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
if ([obj respondsToSelector:#selector(jsonObject)])
[array addObject:[obj jsonObject]];
else
[array addObject:obj];
}];
return [NSArray arrayWithArray:array];
}
#end
If you do something like that, you can now convert arrays or dictionaries of your custom objects object into something that can be used for generating JSON:
NSArray *products = #[[[Product alloc] initWithName:#"Prius" color:#"Green" quantity:3],
[[Product alloc] initWithName:#"Accord" color:#"Black" quantity:1],
[[Product alloc] initWithName:#"Civic" color:#"Blue" quantity:2]];
id productsJsonObject = [products jsonObject];
NSError *error = nil;
NSData *data = [NSJSONSerialization dataWithJSONObject:productsJsonObject options:0 error:&error];
If you're simply trying to save these objects in a file, I'd suggest NSKeyedArchiver and NSKeyedUnarchiver. But if you need to generate JSON objects for your own private classes, you can do something like the above might work.
In .h File
#import <Foundation/Foundation.h>
#interface ContactDetail : NSObject
#property (nonatomic) NSString *firstName;
#property (nonatomic) NSString *lastName;
#property (nonatomic) NSString *fullName;
#property (nonatomic) NSMutableArray *mobileNumbers;
#property (nonatomic) NSMutableArray *Emails;
#property (assign) bool Isopen;
#property (assign) bool IsChecked;
-(NSDictionary *)dictionary;
#end
in .m file
#import "ContactDetail.h"
#import <objc/runtime.h>
#implementation ContactDetail
#synthesize firstName;
#synthesize lastName;
#synthesize fullName;
#synthesize mobileNumbers;
#synthesize Emails;
#synthesize IsChecked,Isopen;
//-(NSDictionary *)dictionary {
// return [NSDictionary dictionaryWithObjectsAndKeys:self.fullName,#"fullname",self.mobileNumbers,#"mobileNumbers",self.Emails,#"emails", nil];
//}
- (NSDictionary *)dictionary {
unsigned int count = 0;
NSMutableDictionary *dictionary = [NSMutableDictionary new];
objc_property_t *properties = class_copyPropertyList([self class], &count);
for (int i = 0; i < count; i++) {
NSString *key = [NSString stringWithUTF8String:property_getName(properties[i])];
id value = [self valueForKey:key];
if (value == nil) {
// nothing todo
}
else if ([value isKindOfClass:[NSNumber class]]
|| [value isKindOfClass:[NSString class]]
|| [value isKindOfClass:[NSDictionary class]] || [value isKindOfClass:[NSMutableArray class]]) {
// TODO: extend to other types
[dictionary setObject:value forKey:key];
}
else if ([value isKindOfClass:[NSObject class]]) {
[dictionary setObject:[value dictionary] forKey:key];
}
else {
NSLog(#"Invalid type for %# (%#)", NSStringFromClass([self class]), key);
}
}
free(properties);
return dictionary;
}
#end
if any crash ,You check the property (NSMutableArray,NSString,etc ) in else if condition inside of for.
In Your Controller, in any func...
-(void)addItemViewController:(ConatctViewController *)controller didFinishEnteringItem:(NSMutableArray *)SelectedContact
{
NSLog(#"%#",SelectedContact);
NSMutableArray *myData = [[NSMutableArray alloc] init];
for (ContactDetail *cont in SelectedContact) {
[myData addObject:[cont dictionary]];
}
NSError *error = nil;
NSData *jsonData = [NSJSONSerialization dataWithJSONObject:myData options:NSJSONWritingPrettyPrinted error:&error];
if ([jsonData length] > 0 &&
error == nil){
// NSLog(#"Successfully serialized the dictionary into data = %#", jsonData);
NSString *jsonString = [[NSString alloc] initWithData:jsonData
encoding:NSUTF8StringEncoding];
NSLog(#"JSON String = %#", jsonString);
}
else if ([jsonData length] == 0 &&
error == nil){
NSLog(#"No data was returned after serialization.");
}
else if (error != nil){
NSLog(#"An error happened = %#", error);
}
}
Try this:
#import <objc/runtime.h>
+ (NSDictionary *)dictionaryWithPropertiesOfObject:(id)obj {
NSMutableDictionary *dict = [NSMutableDictionary dictionary];
unsigned count;
objc_property_t *properties = class_copyPropertyList([obj class], &count);
for (int i = 0; i < count; i++) {
NSString *key = [NSString stringWithUTF8String:property_getName(properties[i])];
[dict setObject:[obj valueForKey:key] ? [obj valueForKey:key] : #"" forKey:key];
}
free(properties);
return [NSDictionary dictionaryWithDictionary:dict];
}
The perfect way to do this is by using a library for serialization/deserialization
many libraries are available but one i like is
JagPropertyConverter
https://github.com/jagill/JAGPropertyConverter
it can convert your Custom object into NSDictionary and vice versa
even it support to convert dictionary or array or any custom object within your object (i.e Composition)
JAGPropertyConverter *converter = [[JAGPropertyConverter alloc]init];
converter.classesToConvert = [NSSet setWithObjects:[ProductDetails class], nil];
//For Object to Dictionary
NSDictionary *dictDetail = [converter convertToDictionary:detail];
NSDictionary* json = [NSJSONSerialization JSONObjectWithData:dictDetail options:NSJSONWritingPrettyPrinted error:&error];
You can convert object (say modelObject) to dictionary at runtime with the help of objc/runtime.h class but that has certain limitations and is not recommended.
Considering MVC, mapping logic should be implemented in Model class.
#interface ModelObject : NSObject
#property (nonatomic) NSString *p1;
#property (nonatomic) NSString *p2;
-(NSDictionary *)dictionary;
#end
#import "ModelObject.h"
#implementation ModelObject
-(NSDictionary *)dictionary
{
NSMutableDictionary *dict = [[NSMutableDictionary alloc] init];
[dict setValue:self.p1 forKey:#"p1"];// you can give different key name here if you want
[dict setValue:self.p2 forKey:#"p2" ];
return dict;
}
#end
Uses:
NSDictionary *modelObjDict = [modelObj dictionary];
Try using
NSDictionary *dict = [details valuesForAttributes:#[#"name", #"color"]];
And compare what the dictionary contains. Then try to convert it to JSON. And look at the JSON spec - what data types can go into a JSON encoded file?
You also can use the NSObject+APObjectMapping category which is available on GitHub: https://github.com/aperechnev/APObjectMapping
It's a quit easy. Just describe the mapping rules in your class:
#import <Foundation/Foundation.h>
#import "NSObject+APObjectMapping.h"
#interface MyCustomClass : NSObject
#property (nonatomic, strong) NSNumber * someNumber;
#property (nonatomic, strong) NSString * someString;
#end
#implementation MyCustomClass
+ (NSMutableDictionary *)objectMapping {
NSMutableDictionary * mapping = [super objectMapping];
if (mapping) {
NSDictionary * objectMapping = #{ #"someNumber": #"some_number",
#"someString": #"some_string" };
}
return mapping
}
#end
And then you can easily map your object to dictionary:
MyCustomClass * myObj = [[MyCustomClass alloc] init];
myObj.someNumber = #1;
myObj.someString = #"some string";
NSDictionary * myDict = [myObj mapToDictionary];
Also you can parse your object from dictionary:
NSDictionary * myDict = #{ #"some_number": #123,
#"some_string": #"some string" };
MyCustomClass * myObj = [[MyCustomClass alloc] initWithDictionary:myDict];
Swift
Now the swift is very popular and most of the SDK's are written in Objective C, we need to convert NSObject to NSDictionary, With the Help of #thatzprem Answer, I wrote an extension for Swift which will convert our NSObject into NSDictionary, then we can use that NSDictionary to simple Dictionary or JSON Object or other purpose. I hope so this will help out the Swift User.
extension NSObject {
func convertNSObjectToNSDictionary() -> [AnyHashable : Any]? {
var dict: [AnyHashable : Any] = [:]
var count: UInt32 = 0
let properties = class_copyPropertyList(type(of: self), UnsafeMutablePointer<UInt32>(mutating: &count)) //as? objc_property_t
for i in 0..<Int(count) {
var key: String? = nil
if let property = properties?[i] as? objc_property_t {
key = String(utf8String: property_getName(property))
}
//dict[key] = (obj as? NSObject)?.value(forKey: key ?? "")
dict[key] = (self).value(forKey: key ?? "")
}
free(properties)
return dict
}
}
Can't find out why my code doesn't work. Please help someone.
I created my own class, implemented NSCoding protocol. Do not know what i miss or wrong.
Here is saving code
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory , NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *fileName = [documentsDirectory stringByAppendingPathComponent:#"Currency.plist"];
Item * item = [[Item alloc] init];
item.x = 3; item.y = 5; item.type = (TType) 3; item.isSelected = NO;
NSMutableArray * array = [[NSMutableArray alloc] init];
[array addObject:item];
[array fileName atomically:YES] // ( Doesn't Save the file ,returns NO);
Here is the code of my class
*.h*
#import <Foundation/Foundation.h>
enum TType
{
kNone = 0,
KFirst = 1,
....
};
#interface Item : NSObject <NSCoding>{
}
#property (nonatomic) int x;
#property (nonatomic) int y;
#property (nonatomic) enum TType type;
#property (nonatomic) BOOL isSelected;
#end
.m
#implementation Item
#synthesize x, y , type , isSelected;
#pragma mark NSCoding Protocol
- (void)encodeWithCoder:(NSCoder *)encoder;
{
[encoder encodeInt32:[self x] forKey:#"x"];
[encoder encodeInt32:[self y] forKey:#"y"];
[encoder encodeInt32:[self type] forKey:#"type"];
[encoder encodeBool:[self isSelected] forKey:#"isSelected"];
}
- (id)initWithCoder:(NSCoder *)decoder;
{
if ( ![super init] )
return nil;
[self setX:[decoder decodeInt32ForKey:#"x"]];
[self setY:[decoder decodeInt32ForKey:#"y"]];
[self setType:(TType)[decoder decodeInt32ForKey:#"color"]];
[self setIsSelected:[decoder decodeBoolForKey:#"isSelected"]];
return self;
}
#end
I think you'll find your answer at: objects conforming to nscoding will not writetofile
i.e. you can't serialize your Item class to a property list, since it isn't a property list object (NSString, NSData, NSArray, or NSDictionary).
See the documentation for writeToFile:atomically::
This method recursively validates that all the contained objects are property list objects before writing out the file, and returns NO if all the objects are not property list objects, since the resultant file would not be a valid property list.
I am blocking into something and I am sure it is too big.
I have a custom object that look like this
#interface DownloadObject : NSObject <NSCoding>{
NSNumber *key;
NSString *name;
NSNumber *progress;
NSNumber *progressBytes;
NSNumber *size;
NSString *path;
}
#property (copy) NSNumber *key;
#property (copy) NSString *name;
#property (copy) NSNumber *progress;
#property (copy) NSNumber *size;
#property (copy) NSString *path;
#property (copy) NSNumber *progressBytes;
-(id)initWithKey:(NSNumber *)k name:(NSString *)n progress:(NSNumber *)pro size:(NSNumber *)s path:(NSString *)p progressBytes:(NSNumber *)pb;
#end
And the implementation
#implementation DownloadObject
#synthesize size, progress, name, key, path, progressBytes;
-(id)initWithKey:(NSNumber *)k name:(NSString *)n progress:(NSNumber *)pro size:(NSNumber *)s path:(NSString *)p progressBytes:(NSNumber *)pb
{
self.key = k;
self.name = n;
self.progress = pro;
self.size = s;
self.path = p;
self.progressBytes = pb;
return self;
}
-(id) initWithCoder: (NSCoder*) coder {
if (self = [super init]) {
self.key = [[coder decodeObjectForKey:#"Key"] retain];
self.name = [[coder decodeObjectForKey:#"Name"] retain];
self.progress = [[coder decodeObjectForKey:#"Progress"] retain];
self.size = [[coder decodeObjectForKey:#"Size"] retain];
self.path = [[coder decodeObjectForKey:#"Path"] retain];
self.progressBytes = [[coder decodeObjectForKey:#"ProgressBytes"]retain];
}
return self;
}
-(void) encodeWithCoder: (NSCoder*) coder {
[coder encodeObject:self.key forKey:#"Key"];
[coder encodeObject:self.name forKey:#"Name"];
[coder encodeObject:self.progress forKey:#"Progress"];
[coder encodeObject:self.size forKey:#"Size"];
[coder encodeObject:self.path forKey:#"Path"];
[coder encodeObject:self.progressBytes forKey:#"ProgressBytes"];
}
-(void)dealloc
{
[key release];
[name release];
[size release];
[progress release];
[path release];
[progressBytes release];
[super dealloc];
}
#end
As you can see it implement NSCoding (I think so, NSObject does not conform to NSCoding). Now when I try to do something like that just to test
downloadArray = [[[NSMutableArray alloc]init]retain];
NSNumber *number = [NSNumber numberWithInt:10];
DownloadObject *object = [[DownloadObject alloc]initWithKey:number name:#"hey" progress:number size:number path:#"hey" progressBytes:number];
[downloadArray addObject:object];
[object release];
[downloadArray writeToFile:path atomically:YES];
downloadArray is a NSMutableArray. My plist read/write is fine, the path is located in the application support and when I log it show the plist path.
But it just does not write the array to the plist, any idea ?
Property list files can only store basic data types and cannot contain custom objects. You need to convert your object to an NSData object if you want it to be written to the plist. You can do this with NSKeyedArchiver, which will encode an object which conforms to the NSCoding protocol into an NSData object.
DownloadObject *object = [[DownloadObject alloc]initWithKey:number name:#"hey" progress:number size:number path:#"hey" progressBytes:number];
NSData* objData = [NSKeyedArchiver archivedDataWithRootObject:object];
[downloadArray addObject:objData];
[object release];
When you want to reconstruct your object from the NSData object, you use NSKeyedUnarchiver:
NSData* objData = [downloadArray objectAtIndex:0];
DownloadObject* object = [NSKeyedUnarchiver unarchiveObjectWithData:objData];
You also have several memory leaks in your code. In your -initWithCoder: method, you should not be using accessors to set the value of the ivars, you should just set the ivars directly, like so:
key = [[coder decodeObjectForKey:#"Key"] copy];
You are calling -retain and then using the accessor which is specified as copy, which will mean your object has a retain count of 2 and will not be released. In general you should avoid using accessors in init methods.
Also, in the code where you allocate your downloadArray object, you are calling -alloc and then -retain on the object, which will leave it with a retainCount of 2. You should re-read the Objective-C Memory Management Guidelines.
This works for me:
NSMutableData *data = [[NSMutableData alloc] init];
NSKeyedArchiver *archiver = [[NSKeyedArchiver alloc] initForWritingWithMutableData:data];
[archiver encodeObject:highScoreArray forKey:kHighScoreArrayKey];
[archiver finishEncoding];
[data writeToFile:[self dataFilePath] atomically:YES];
[data release];
[archiver release];
BOOL flag = false;
ObjectFileClass *obj = [yourMutableArray objectAtIndex:0];
//TO Write Data . . .
NSData* archiveData = [NSKeyedArchiver archivedDataWithRootObject:obj.title];
flag =[archiveData writeToFile:path options:NSDataWritingAtomic error:&error];
}
if (flag) {
NSLog(#"Written");
//To Read Data . . .
NSData *archiveData = [NSData dataWithContentsOfFile:path];
id yourClassInstance = [NSKeyedUnarchiver unarchiveObjectWithData:archiveData]; // choose the type of your class instance . . .
NSLog(#"%#",yourClassInstance);
}else{
NSLog(#"Not Written");
}
I had a method to save a dic to the disk:
+(BOOL) writeApplicationData:(NSDictionary *)data
bwriteFileName:(NSString *)fileName
{
NSLog(#"writeApplicationData");
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
if (!documentsDirectory) {
NSLog(#"Documents directory not found!");
return NO;
}
NSString *appFile = [documentsDirectory stringByAppendingPathComponent:fileName];
return ([data writeToFile:appFile atomically:YES]);
}
And I tested it with:
NSMutableDictionary *dic = [[NSMutableDictionary alloc] init];
NSMutableDictionary *d1 = [[NSMutableDictionary alloc] init];
NSMutableDictionary *d2 = [[NSMutableDictionary alloc] init];
[d1 setObject:#"d11"
forKey:#"d11"];
[d1 setObject:#"d12"
forKey:#"d12"];
[d1 setObject:#"d13"
forKey:#"d13"];
[d2 setObject:#"d21"
forKey:#"d21"];
[d2 setObject:#"d22"
forKey:#"d22"];
[d2 setObject:#"d23"
forKey:#"d23"];
[dic setObject:d1
forKey:#"d1"];
[dic setObject:d2
forKey:#"d2"];
[self writeApplicationData:dic
bwriteFileName:#"testSave"];
And the data is saved correctly.
Then I tried to save d1 with class obj in it:
LevelInfoData *levelInfoData = [[LevelInfoData alloc] init];
[levelInfoDictionary setObject:levelInfoData
forKey:#"test"];
[dic setObject:levelInfoDictionary
forKey:#"LevelInfoDictionary"];
But this time, even no plist file was generated in the disk.
Here is the LevelInfoData class:
#interface LevelInfoData : NSObject {
int levelNum;
}
#property (nonatomic) int levelNum;
#end
#implementation LevelInfoData
#synthesize levelNum;
#synthesize isLevelLocked;
#synthesize isLevelCleared;
#synthesize levelHighScore;
-(id)init
{
if( (self = [super init]) ) {
levelNum = 0;
}
return self;
}
#end
I'm really confused, hope somebody could help me out, thanks.
The contents of the dictionary need to be property list type objects.
From the NSDictionary Class Reference:
This method recursively validates that all the contained objects are property list objects (instances of NSData, NSDate, NSNumber, NSString, NSArray, or NSDictionary) before writing out the file, and returns NO if all the objects are not property list objects, since the resultant file would not be a valid property list.
https://developer.apple.com/library/ios/#documentation/Cocoa/Reference/Foundation/Classes/NSDictionary_Class/Reference/Reference.html
You may want to try making your custom class a subclass of NSData rather than NSObject.
I'm not sure how attached you are to NSDictionary, but this may be a situation where NSCoder will better serve you.
See nscoder vs nsdictionary when do you use what
More details here:
NSCoder Class Reference
Some code snippets
A tutorial
Alright guys, I'm quite confused. So, I have an NSDictionary which is populated by a JSON string which looks like:
{"Success":true,"Devices":[{"UDId":"...","User":"...","Latitude":0.0,"Longitude":0.0}]}
Now, I know how to check if Success is true, but I need to loop through the array of Devices (JSON object) and create an internal array of Devices (internal app object) and I have no idea how to do that. Can someone please explain how to do it?
Here's my Device.m/h:
#import <CoreLocation/CoreLocation.h>
#import <Foundation/Foundation.h>
#interface Device : NSObject {
NSString *udId;
NSString *name;
NSNumber *latitude;
NSNumber *longitude;
}
#property (nonatomic, retain) NSString *udId;
#property (nonatomic, retain) NSString *name;
#property (nonatomic, retain) NSNumber *latitude;
#property (nonatomic, retain) NSNumber *longitude;
#pragma mark -
#pragma mark MKAnnotation Properties
#property (nonatomic, readonly) CLLocationCoordinate2D coordinate;
#end
----
#import "Device.h"
#implementation Device
#synthesize udId, name, latitude, longitude;
- (CLLocationCoordinate2D)coordinate {
CLLocationCoordinate2D internalCoordinate;
internalCoordinate.latitude = [self.latitude doubleValue];
internalCoordinate.longitude = [self.longitude doubleValue];
return internalCoordinate;
}
- (void)dealloc {
[udId release];
udId = nil;
[name release];
name = nil;
[latitude release];
latitude = nil;
[longitude release];
longitude = nil;
[super dealloc];
}
#end
And here's the methods where I should be reading the response and converting it to objects I can use:
- (void)requestFinished:(ASIHTTPRequest *)request {
if (![request error]) {
NSError *jsonError = nil;
NSDictionary *jsonDictionary = [NSDictionary dictionaryWithJSONString:[request responseString] error:&jsonError];
if (!jsonError || ([[jsonDictionary objectForKey:#"Success"] intValue] == 1)) {
// READ "DEVICES" AND CONVERT TO OBJECTS
} else {
// AUTHORIZATION FAILED
}
}
}
I'd really appreciate some help on this. I just can't seem to wrap my head around it...
Thanks in advance!
You are almost there. In your code where you say:
// READ "DEVICES" AND CONVERT TO OBJECTS
do this:
NSArray * devices = [jsonDictionary objectForKey:#"Devices"];
for(NSDictionary * deviceInfo in devices) {
Device * d = [[[Device alloc] init] autorelease];
[d setLatitude:[deviceInfo objectForKey:#"Latitude"]];
[d setLongitude:[deviceInfo objectForKey:#"Longitude"]];
[d setName:[deviceInfo objectForKey:#"User"]];
[d setUdId:[deviceInfo objectForKey:#"UDId"]];
// do some stuff with d
}
What's going on here: I didn't see what JSON library you are using to convert, but presuming it works like TouchJSON or SBJSON, the JSON array is automatically turned into an NSArray instance, while the inner hashes of the NSArray are NSDictionary objects. At the point that you have deserialized that JSON string, everything you're dealing with will be instances of NSString, NSNumber, NSArray and NSDictionary (and depending on the library, NSNull to represent null values).
First you need to define your initializer/constructor for your Device class.
Device.h
- (id)initWithUdid:(NSString *)udid name:(NSString *)name latitude:(NSNumber *)lat longitude:(NSNumber *)lon;
Device.m
- (id)initWithUdid:(NSString *)udid name:(NSString *)name latitude:(NSNumber *)lat longitude:(NSNumber *)lon {
if (self = [super init]) {
self.udid = udid;
self.name = name;
self.latitude = lat;
self.longitude = lon;
}
return self;
}
Then you can initialize a new object like:
Device *dev = [[Device alloc] initWithUdid:#"a udid" name:#"the name" latitude:latNum longitude:lonNum];
So, you should be able to iterate the array and build your Device objects like so:
NSArray *devicesArray = [dict objectForKey:#"Devices"];
for (NSDictionary *d in devicesArray) {
Device *dev = [[Device alloc] initWithUdid:[d objectForKey:#"UDId"]
name:[d objectForKey:#"User"]
latitude:[NSNumber numberWithDouble:[d objectForKey:#"Latitude"]]
longitude:[NSNumber numberWithDouble:[d objectForKey:#"Latitude"]]];
}
You want to access the array of device dictionaries from the top-level dictionary just as you did the Success value. Then iterating over the dictionaries you can use each's -keyEnumerator method to iterate over its keys.
- (void)requestFinished:(ASIHTTPRequest *)request {
if (![request error]) {
NSError *jsonError = nil;
NSDictionary *jsonDictionary = [NSDictionary dictionaryWithJSONString:[request responseString] error:&jsonError];
if (!jsonError || ([[jsonDictionary objectForKey:#"Success"] intValue] == 1)) {
NSArray* deviceArray = [jsonDictionary objectForKey:#"Devices"];
for(NSDictionary* dict in deviceArray)
{
for(NSString* key in [dict keyEnumerator])
{
NSLog(#"%# -> %#", key, [dict objectForKey:key]);
}
}
// READ "DEVICES" AND CONVERT TO OBJECTS
} else {
// AUTHORIZATION FAILED
}
}
}
Sounds like you need to reuse your line:
[jsonDictionary objectForKey:#"Success"]
try having a look at
[jsonDictionary objectForKey:#"Devices"]
You really need to figure out what type it returns.
If you're lucky, it returns an NSDictionary, or alternately something that you can easily turn into an NSDictionary.