Newbie Question,
I am playing with NSMutableArray *myBook that contains card elements (name and email address).
I want myBook displayed with descending list.
AddressBook.h
#import <Foundation/Foundation.h>
#import "AddressCard.h"
#interface AddressBook : NSObject
#property (nonatomic, copy) NSMutableString *bookName;
#property (nonatomic , strong) NSMutableArray *book;
AddressCard.h
#import <Foundation/Foundation.h>
#interface AddressCard : NSObject
#property (nonatomic, copy) NSMutableString *name, *email;
AddressBook.m
- (void) sort{
[book sortUsingSelector:#selector(compareNames:)];
}
- (void) showList{
NSLog(#"====== Contents of: %# =======",bookName);
for (AddressCard *theCard in book) {
NSLog(#"%-20s %-32s", [theCard.name UTF8String], [theCard.email UTF8String] );
}
NSLog(#"===============================");
}
AddressCard.m
- (NSComparisonResult) compareNames: (id) element{
return [name compare:[element name]];
}
my CompareNames method returns Ascending result. How do I make it to return Descending?
Thanks !
while - (void)sortUsingSelector:(SEL)comparator method suppose to sorts the array's elements in ascending order, the comparator method should return NSOrderedAscending if the array is smaller than the argument, NSOrderedDescending if the array is larger than the argument, and NSOrderedSame if they are equal.
Since the NSComparisonResult define as:
enum {
NSOrderedAscending = -1,
NSOrderedSame,
NSOrderedDescending
};
typedef NSInteger NSComparisonResult;
All you need is a descendingComparator, something like:
- (NSComparisonResult)compareNameInDesendingOrder:(AddressCard *)aCard {
return -[self.name compare:[aCard name]];
}
- (void)sortInDesendingOrder {
[book sortUsingSelector:#selector(compareNameInDesendingOrder:)];
}
hope it helps.
Related
I think it's very difficult to print out the value of all properties of any class in objective-c, in the case the type of the property is complex.
But if the class that contains properties with simple types (like, NSString, int, double, boolean), is there any way to NSLog automatically instead of NSLog manually the value of each property?
Updated:
All the solutions you gave me are still manually. Is there any way like iterate through all properties of a class, and NSLog the variable_name and the variable_value. That's what I expected.
You can do this by overriding -(void)description method.
Example:
Let's say we have simple Car class.
#interface Car : NSObject
#property (copy, nonatomic) NSString *model;
#property (copy, nonatomic) NSString *make;
#property (strong, nonatomic) NSDate *registrationDate;
#property (assign, nonatomic) NSInteger mileage;
#property (assign, nonatomic) double fuelConsumption;
#end
#implementation
- (NSString*)description {
return [NSString stringWithFormat:#"<%#:%p %#>",
[self className],
self,
#{ #"model" : self.model,
#"make" : self.make,
#"registrationDate": self.registrationDate,
#"mileage" : #(self.mileage),
#"fuelConsumption" : #(self.fuelConsumption)
}];
}
#end
Putting this in NSDictionary will create very nice output in console.
On the other hand, you can create category on NSObject class and do something like this:
- (NSString*)myDescriptionMethod {
NSMutableDictionary *dict = [NSMutableDictionary new];
unsigned int count;
objc_property_t *properties = class_copyPropertyList([self class], &count);
for (int i = 0; i < count; i++) {
const char *property = property_getName(properties[i]);
NSString *propertyString = [NSString stringWithCString:property encoding:[NSString defaultCStringEncoding]];
id obj = [self valueForKey:propertyString];
[dict setValue:obj forKey:propertyString];
}
free(properties);
return [NSString stringWithFormat:#"<%# %p %#>",
[self class],
self,
dict];
}
Then you will avoid overriding -(void)description method in your classes.
Get it from here
The most elegant way to achieve what you're looking for in Objective-C with NSObject subclasses, it to override the NSObject method description.
For example (assuming your Class has a property called propertyX):
-(NSString *)description
{
return [NSString stringWithFormat:#"<myCustomObject: %#, propertyX: %f, %f>",
[self objectID], [self propertyX].x, [self propertyX].y];
}
The default description implementation of NSObject will simply return the memory address pointed to for the object, like so:
NSLog(#"%#", self);
2015-06-15 14:20:30.123 AppName[...] myCustomObject: 0x000000>
However, by overriding this base Class method as shown above, you will be able to customise this behavior, and the log will look like this:
2015-06-15 14:20:30.123 AppName[...] myCustomObject: 0x000000 someProperty, Property: blah, blah>
There is a nice tutorial, which discusses this further here.
Example :-
+ (NSString *)description;
[NSString description];
Gives you information about the class NSString.
I have the json
{"Types":{
"food":[{"cve":"1","description":"Pizza"},{"cve":"2","description":"Restaurant"},{"cve":"3","description":"Cafe"}],
"Health":[{"cve":"3","description":"Pharmacy"},{"cve":"4","description":"Hospital"}]
} }
Types.h
#import <Foundation/Foundation.h>
#interface Types: NSObject
#property (nonatomic, copy) NSDictionary *types;
#end
Types.m
#import "Types.h"
#import <Motis/Motis.h>
#import "SubTipo.h"
#implementation Types
+ (NSDictionary*)mts_mapping
{
return #{#"types": mts_key(types),};
}
#end
Subtype.h
#import <Foundation/Foundation.h>
#interface Subtype: NSObject
#property (nonatomic, assign) int cve;
#property (nonatomic, copy) NSString *description;
#end
Subtype.m
#import "Subtype.h"
#import <Motis/Motis.h>
#implementation Subtype
+ (NSDictionary*)mts_mapping
{
return #{#"cve": mts_key(cve),
#"description": mts_key(description),
};
}
#end
I deserialize with
Types * values=[[Types alloc]init];
NSDictionary * jsonObject = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers error:&error];
[values mts_setValuesForKeysWithDictionary:jsonObject ];
I get NSDictionary with NSArray of NSDictionary
but I need NSDictionary with NSArray of Subtypes
I try with
+ (NSDictionary*)mts_arrayClassMapping
{
return #{mts_key(types): Subtype.class};
}
but wasn't successful
How can I get these with Motis
As far as I see, your Types object is not properly defined. If you have an attribute of type NSDictionary* and the JSON received is a Dictionary, Motis won't perform any automatic conversion as the types already match (you are receiving a dictionary and your attribute is of type NSDictionary).
Therefore, you must implement your Type object following your JSON structure. This means that your Type object must have two properties of type array, one for food and one for health. Then, using the method +mts_arrayClassMapping you can specify the content type of the arrays to Subtype.
Here the implementation:
// ***** Type.h file ***** //
#interface Type: NSObject
#property (nonatomic, strong) NSArray *food;
#property (nonatomic, strong) NSArray *health;
#end
// ***** Type.m file ***** //
#implementation Type
+ (NSDictionary*)mts_mapping
{
return #{#"food": mts_key(food),
#"Health": mts_key(health),
};
}
+ (NSDictionary*)mts_arrayClassMapping
{
return #{mts_key(food): Subtype.class,
mts_key(health): Subtype.class,
};
}
#end
Regarding the implementation of Subtype, yours is already correct. However, you should not use the property name description as it is already being used by NSObject:
// ***** Subtype.h file ***** //
#interface Subtype: NSObject
#property (nonatomic, assign) NSInteger cve;
#property (nonatomic, copy) NSString *theDescription;
#end
// ***** Subtypes.m file ***** //
#implementation Subtype
+ (NSDictionary*)mts_mapping
{
return #{#"cve": mts_key(cve),
#"description": mts_key(theDescription),
};
}
#end
Finally, as you list above, you can map your JSON, but first you will have to extract the "dictionary" for key Types, which you will map to your "Type" model object.
// Get the json data
NSDictionary * jsonObject = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers error:&error];
// Extract the JSON dictionary of types.
NSDictionary *jsonType = [jsonObject objectForKey:#"Types"];
// Create a Type object
Type *type = [[Type alloc] init];
// Map JSON contents to the type object with Motis
[type mts_setValuesForKeysWithDictionary:jsonType];
Hoping this fixes your issue.
Using Objective-C, is it possible to go through an array by groups :
exemple :
NSArray *arr = 1, 2, 3, ....100;
Every 10 objects, do something and go on
so :
object 0 to 9 : you do something with each object and after the 10° object you do a last action
then object 10 to 19 : you do something with each object and after the 19° object you do a last action
and so on until the last object
thank you for your help
something like this:
for (int i = 0; i < arr.count; i++)
{
[self doSomethingWithArray];
if (i % 10 == 0)
[self doSomethingElse];
}
No it is not possible in Objective-C with in-built functions which matches your exact description. There are crude ways to do it by loops which matches your exact description.
But if you are aware before hand that you are going to make such type of operations, define your own data-structure. Create an NSObject sub-class, define your items (10 items which you were talking about) in it. Then in array, you can directly take out each instance of it comprising of your defined NSObject.
"enumerating by group"; If you want exactly as stated, you can subclass NSEnumerator.
For example:
In your Application code:
#import "NSArray+SubarrayEnumerator.h"
NSArray *arr = ...;
for(NSArray *grp in [arr subarrayEnumeratorEach:10]) {
// do what you want.
}
NSArray+SubarrayEnumerator.h
#import <Foundation/Foundation.h>
#interface NSArray (SubarrayEnumerator)
- (NSEnumerator *)subarrayEnumeratorEach:(NSUInteger)perPage;
#end
NSArray+SubarrayEnumerator.m
#import "NSArray+SubarrayEnumerator.h"
#interface _NSArraySubarrayEnumeratorEach : NSEnumerator
#property (assign, nonatomic) NSUInteger cursor;
#property (assign, nonatomic) NSUInteger perPage;
#property (strong, nonatomic) NSArray *src;
#end
#implementation NSArray (SubarrayEnumerator)
- (NSEnumerator *)subarrayEnumeratorEach:(NSUInteger)perPage {
_NSArraySubarrayEnumeratorEach *enumerator = [[_NSArraySubarrayEnumeratorEach alloc] init];
enumerator.perPage = perPage;
enumerator.src = self;
return enumerator;
}
#end
#implementation _NSArraySubarrayEnumeratorEach
- (id)nextObject {
NSUInteger start = _cursor;
if(start >= _src.count) {
return nil;
}
NSUInteger count = MIN(_perPage, _src.count - start);
_cursor += _perPage;
return [_src subarrayWithRange:NSMakeRange(start, count)];
}
#end
I'm new to iphone app development and I'm stuck on this problem I'm having with the app I'm trying to develop.
I have a datacontroller for populating a tableview. I created it using this tutorial:
About Creating Your Second iOS App
I'm trying to pass an array from one of my viewcontrollers that was created from a JSON response.
Here is some code from my viewcontroller.h that needs to pass the array:
#interface ViewController : UIViewController
#property (nonatomic, retain) DataController *Data;
#property (nonatomic, retain) NSMutableArray *array;
#end
viewcontroller.m:
#import "DataController.h"
[Data setMasterList: self.array];
DataController.h:
#interface DataController : NSObject
#property (nonatomic, strong) NSMutableArray *masterList;
- (void)setMasterList:(NSMutableArray *)newList;
#end
DataController.m
#import "LoginViewController.h"
- (void)setMasterList:(NSMutableArray *)newList {
if (_masterList != newList) {
_masterList = [newList mutableCopy];
NSLog("List: %#", newList);
}
}
The NSLog message never shows up in the console and the array is nil.
Any help is appreciated.
Thanks.
EDIT:
Here's the updated viewcontroller.m:
Data = [[DataController alloc] init];
[Data setMasterList: self.array];
The datacontroller.m:
- (void)setMasterList:(NSMutableArray *)newList {
if (_masterList != newList) {
_masterList = [newList mutableCopy];
NSLog("List: %#", self.masterList);
}
}
- (NSUInteger)countOfList {
NSLog("List: %#", self.masterList);
return [self.masterList count];
}
The first nslog inside setMasterList returns the correct array values, but the second nslog inside countOfList returns null. The list always returns null anywhere outside of setMasterList. Is it because I'm creating a new instance of the DataController? If so, how else could I pass the array to the datacontroller.
As in first comment Till have suggested, Data must be initialized before calling setMasterList. Such As:
Data = [[DataController alloc] init];
[Data setMasterList: self.array];
please help me to solve a simple problem.
I am a beginner in objective-c, and I am just switched to objective-c from java. I know java fair well, but not quite super deep into it.
I am building a iphone app. My app is quite simple.
The purpose of my iphone app is to take order with my iphone app in a restaurant.
Progress of My App:
My app only has couple viewPanels and buttons now :)
Here is my app sourcecode, firstview screenshot & secondview screenshot
Problem:
When i click on the Coffee button, my textField wont show up the coffee name & coffee price, which suppose to show up " coffee 1" .
and xcode will take me to the debugger from the iphone similator.(i think its crush at a line so the dubugger took me to the IBaction method and break at the line #synthesize name; It compiles with no error. please help trouble shoot why xcode take me to debugger when i press the coffee button.
SCREEN SHOWS UP RIGHT AFTER PRESS THE COFFEE BUTTON
here is the action code of the coffee button
- (IBAction)Coffee:(id)sender {
int price = 1;
NSString *name = #"coffee";
Storage *order = [[Storage alloc] init];
[order setName:name]; // i assume the program crush at here when it look into setName method.
[order setPrice:price];
[orders addOrders:order];
// Sanity check: // the program not even hit this line yet before crush;
NSLog(#"There are now %d orders in the array.", [orders.getOrders count]);
for (Storage *obj in orders.getOrders){
[check setText:[NSString stringWithFormat:#"%#",[obj description]]]; // check is the TextField instant varible. and the description method is from storage.m to print out the name and price.
}
}
The codes below are my storage classes that store all items that my customer orders.
it is a 2 dimensional array, and My Storages class is a wrapper class of Storage class.
the array format looks like this:
arrayindex1-> name, price
arrayindex2-> name, price
arrayindex3-> name, price
arrayindex4-> name, price
Storage.h
#import <Foundation/Foundation.h>
#interface Storage : NSObject
#property (nonatomic, strong) NSString *name;
#property (nonatomic, assign) NSInteger price;
#end
Storage.m
#import "Storage.h"
#implementation Storage
#synthesize name; // program crush and goes to here.
#synthesize price;
- (NSString *)description {
// example: "coffee 1"
return [NSString stringWithFormat:#"%# %d", self.name, self.price];
}
#end
Storages.h
#import <Foundation/Foundation.h>
#import "Storage.h"
#interface Storages : NSObject
#property (nonatomic,strong, readwrite) NSMutableArray *orders;
-(void) addOrders:(Storage *)anOrder;
-(NSMutableArray *) getOrders;
#end
Storages.m
#import "Storages.h"
#implementation Storages
#synthesize orders;
- (id)init {
self = [super init];
if (self) {
orders = [[NSMutableArray alloc] init];
}
return self;
}
-(void) addOrders:(Storage *)anOrder{
[orders addObject: anOrder];
}
-(NSMutableArray *) getOrders{
return orders;
}
#end
There are a couple of problems here.
1) Don't use a pointer for the price property. Generally, unless you're doing something unusual, your properties that are objects will be pointers and your properties that are primitives (NSInteger, BOOL, float, etc) will not be pointers.
2) You will want to make sure that the orders NSMutableArray is initialized with the Storages object, otherwise orders will remain nil and whenever you try to add objects to it, nothing will happen. To initialize the NSMutableArray, do this in your init method as shown below. You can also check that the object is actually getting into a valid mutable array this by putting a simple NSLog statement in the for (Storage *obj in orders.getOrders) { ... } loop and making sure you get at least one iteration through the loop. If orders.getOrders is nil, the work block of the for loop will never get run.
3) It sounds like you need to override (and may have already overridden) the -[NSObject description]method for your Storage object. My guess is you have a mismatch in this method with the -[NSString stringWithFormat:...] format string. For example, you might be using %d or %# in the format string for the NSInteger *. Something like that could definitely cause a crash (which is what I think you mean by "Xcode taking you to the debugger"). For NSIntegers you need to use %d or %i. And as myself and others have mentioned, you want NSInteger here and not NSInteger * and you should change your property declaration.
4) Based on what you have here, I don't think you need the order property in the Storages class at all.
5) Make sure you haven't overlooked the possibility of forgetting to hook up the IBOutlet in Interface Builder to the check textField. A good test for this, besides just confirming it's connected in Interface Builder, would be a reality check test like [check setText:#"This is a test."];
6) Keep in mind that once this works, your for loop is going to execute very quickly, and you'll immediately see only the description for the last object in the orders array. But that doesn't seem to be what your question is about.
I'd suggest you make the following changes:
Storage.h
#import <Foundation/Foundation.h>
#interface Storage : NSObject
#property (nonatomic, strong) NSString *name;
#property (nonatomic, assign) NSInteger price;
#end
Storage.m
#import "Storage.h"
#implementation Storage
#synthesize name;
#synthesize price;
- (NSString *)description {
// example: "coffee 1"
return [NSString stringWithFormat:#"%# %d", self.name, self.price];
}
#end
Your IBAction method
- (IBAction)Coffee:(id)sender {
int price = 1;
NSString *name = #"coffee";
Storage *order = [[Storage alloc] init];
[order setName:name];
[order setPrice:price];
[orders addOrders:order];
// Sanity check:
NSLog(#"There are now %d orders in the array.", [orders.getOrders count]);
for (Storage *obj in orders.getOrders){
[check setText:[NSString stringWithFormat:#"%#",[obj description]]]; // check is the TextField instant varible. and the description method is from storage.m to print out the name and price.
}
}
Storages.h
#import <Foundation/Foundation.h>
#import "Storage.h"
#interface Storages : NSObject
#property (nonatomic,strong, readwrite) NSMutableArray *orders;
-(void) addOrders:(Storage *)anOrder;
-(NSMutableArray *) getOrders;
#end
Storages.m
#import "Storages.h"
#implementation Storages
#synthesize orders;
- (id)init {
self = [super init];
if (self) {
orders = [[NSMutableArray alloc] init];
}
return self;
}
-(void) addOrders:(Storage *)anOrder{
[orders addObject: anOrder];
}
-(NSMutableArray *) getOrders{
return orders;
}
#end
What does description do in the following? (I cannot see any description object in Storage class):
[check setText:[NSString stringWithFormat:#"%#",[obj description]]];
I think if you want to print the name the do like:
[check setText:[NSString stringWithFormat:#"%#: %#",obj.name, obj.price]];
You have taken NSInteger pointer in Storages class which is not correct. NSInteger is basic data type and not a pointer. Remove that pointer and use NSInteger variable.
I hope this would resolve your problem.
You could use below code:
#interface Storage : NSObject
#property (nonatomic, retain)NSString *name;
#property (nonatomic, assign)NSInteger price;
You have two mistakes:
1- You declared price as an NSInteger and passed it as a reference. The correct is to pass it as an integer as it is and deal with it as an integer through the whole application.
2- You didn't initialize orders array in Storages class so it will be always nil and will not hold any added object.
You code may looks like:
In the button's IBAction pass the price directly
[order setPrice:price];
In the Storage class
- (NSString *)description {
return [NSString stringWithFormat: #"%# %d", name, price];
}
Add the following to the Storages class
-(id)init
{
if (self = [super init])
{
orders = [[NSMutableArray alloc] init];
}
return self;
}