I'm new in objective-C and here is my problem:
I want to write a game and i want to use a GameStateManager class to manage the game states. As i've read every class in Objective-C should be inherited from NSObject or it's subclass. So here is the GameStateManager interface:
#interface GameStateManager : NSObject {
int currentState_;
}
+(id) instance;
-(void) setState:(int)state;
#end
And here is the implementation:
#implementation GameStateManager
+(id) instance
{
GameStateManager *manager = [GameStateManager init];
return manager;
}
- (id) init
{
self = [super init];
return self;
}
- (void) setState: (int) state
{
switch (state)
{
case GS_MAIN_MENU_START:
{
// MenuScene *menuScene = [MenuScene node];
// [menuScene build: false];
MenuScene *scene = [scene instance:self :false];
[[CCDirector sharedDirector] runWithScene: scene];
}
break;
case GS_PLAYING:
{
}
break;
}
}
#end
I use this class here:
gameStateManager = [GameStateManager instance];
[gameStateManager setState: GS_MAIN_MENU_START];
The second line generated an SIGABRT signal. What's the problem ?
The problem is here:
+ (id) instance
{
GameStateManager *manager = [GameStateManager init];
return manager;
}
In effect you are calling init without ever calling alloc. I’d recommend that you forget about the instance stuff and use the official init patterns until you are really comfortable with the memory management:
- (id) init
{
self = [super init];
if (self == nil)
return nil;
…
return self;
}
…and then get your instance by calling [[GameStateManager alloc] init].
GameStateManager *manager = [GameStateManager init];
-(id)init is an instance method, not a class method. That line should look like this:
GameStateManager *manager = [[GameStateManager alloc] init];
The issue is that the gameStateManager isn't being created properly. Instead of
[GameStateManager init]
use
[[[GameStateManager alloc] init] autorelease]
The autorelease is for good memory management and doesn't actually affect the initialization.
Related
I have a Gamehud where I want to display an object's name. There are lots of objects/sprites in main scene what I am trying to do is to display selected(on touch) objects' name on Gamehud.
Problem is if I alloc Gamehud in CCsprite class it creates new instance and does not update current Gamehud. If I use something like GameHUD *gamehud= (GameHUD *)[self.parent getChildByTag:99]; nothing happens I cannot send the object to GameHud class.
So what would be the correct way to update game hud in a ccsprite or ccnodeclass?
Main Scene;
-(id) init
{
if ((self = [super init]))
{
gameHud = [GameHUD gamehud];
[self addChild:gameHud z:2 tag:99];
}
}
My GameHud
+(id) gamehud
{
return [[self alloc] init];
}
-(id) init
{
if ((self = [super init]))
{
//bunch of labels
}
}
-(void)showName: :(Object *)obj
{
NSLog(#"Object name is %#", obj.name);
[_labelSpeed setString:obj.name];
}
In Object Class:CCSprite
-(void) onTouch
{
//obj is the object with name property that I want to use
GameHUD *gamehud= (GameHUD *)[self.parent getChildByTag:99]; // does not send the obj to gamehud and showName is not called
//GameHud *gamehud= [GameHud alloc] init]; // this displays nslog but doesnt update _label
[gamehud showName:obj];
}
First of all use a singlton or you will create a new GameHub everytime you call +(id) gamehud. i think this could be your problem: you add one GameHUD to the scene and call showName: of another object of GameHUD. Another problem is your -(id)init - you dont return self! so you never get your GameHUD
static GameHUD *sharedInstance = nil;
+(id) gamehud {
if( !sharedInstance ) {
sharedInstance = [[GameHUD alloc] init]
}
return sharedInstance;
}
-(id) init {
self = [super init];
if ( self ) {
//bunch of labels
sharedInstance = self;
}
return self; //i dont see this in your code!
}
from now you can access your hud from every point you want and you dont need to handle with tags. Be careful, its not the best way to create a Singleton (ask google). Dont call ..alloc] init] use only [GameHUD gamehud];
-(void) onTouch {
[[GameHUD gamehud] showName:obj];
}
Good Luck!
You may need to create a singleton or something like a semi singleton. Just add new nsobject class name "SingletonGameHud" to your app
SingletonGameHud.h
#import <Foundation/Foundation.h>
#import "GameHUD.h"
//create singleton class to use gamehud in movingobject class
#interface SingletonGameHud : NSObject
{
GameHUD *gamingHud;
}
#property(nonatomic,strong) GameHUD *gamingHud;
+(SingletonGameHud *)sharedInstance;
#end
SingletonGameHud.m
#import "SingletonGameHud.h"
#import "GameHUD.h"
#implementation SingletonGameHud
#synthesize gamingHud=_gamingHud;
+ (SingletonGameHud *)sharedInstance
{
static SingletonGameHud *sharedInstance = nil;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
sharedInstance = [[SingletonGameHud alloc] init];
// Do any other initialisation stuff here
});
return sharedInstance;
}
- (id)init {
if (self = [super init]) {
_gamingHud = [GameHUD hud];
}
return self;
}
#end
in your game scene call
SingletonGameHud *sharedInstance= [SingletonGameHud sharedInstance];
hud = sharedInstance.gamingHud;
[self addChild:hud z:2 tag:99];
in your on touch method call
-(void) onTouch
{
SingletonGameHud *sharedInstance= [SingletonGameHud sharedInstance];
[sharedInstance.gamingHud showName:obj];
}
It's stepping into the ViewDidLoad of the main view controller, and hitting the line calling get all tweets, but I put a breakpoint in the getAllTweets of both the base and derived to see if it just wasn't hitting the derived like I expected.
#implementation WWMainViewControllerTests {
// system under test
WWMainViewController *viewController;
// dependencies
UITableView *tableViewForTests;
WWTweetServiceMock *tweetServiceMock;
}
- (void)setUp {
tweetServiceMock = [[WWTweetServiceMock alloc] init];
viewController = [[WWMainViewController alloc] init];
viewController.tweetService = tweetServiceMock;
tableViewForTests = [[UITableView alloc] init];
viewController.mainTableView = tableViewForTests;
tableViewForTests.dataSource = viewController;
tableViewForTests.delegate = viewController;
}
- (void)test_ViewLoadedShouldCallServiceLayer_GetAllTweets {
[viewController loadView];
STAssertTrue(tweetServiceMock.getAllTweetsCalled, #"Should call getAllTweets on tweetService dependency");
}
- (void)tearDown {
tableViewForTests = nil;
viewController = nil;
tweetServiceMock = nil;
}
The base tweet service:
#implementation WWTweetService {
NSMutableArray *tweetsToReturn;
}
- (id)init {
if (self = [super init]) {
tweetsToReturn = [[NSMutableArray alloc] init];
}
return self;
}
- (NSArray *)getAllTweets {
NSLog(#"here in the base of get all tweets");
return tweetsToReturn;
}
#end
The Mock tweet service:
#interface WWTweetServiceMock : WWTweetService
#property BOOL getAllTweetsCalled;
#end
#implementation WWTweetServiceMock
#synthesize getAllTweetsCalled;
- (id)init {
if (self = [super init]) {
getAllTweetsCalled = NO;
}
return self;
}
- (NSArray *)getAllTweets {
NSLog(#"here in the mock class.");
getAllTweetsCalled = YES;
return [NSArray array];
}
The main view controller under test:
#implementation WWMainViewController
#synthesize mainTableView = _mainTableView;
#synthesize tweetService;
NSArray *allTweets;
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
allTweets = [tweetService getAllTweets];
NSLog(#"was here in view controller");
}
- (void)viewDidUnload
{
[self setMainTableView:nil];
[super viewDidUnload];
// Release any retained subviews of the main view.
}
Since you're able to break in the debugger in viewDidLoad, what's the value of the tweetService ivar? If it's nil, the getAllTweets message will just be a no op. Maybe the ivar isn't being set properly or overridden somewhere else.
You should probably use the property to access the tweetService (call self.tweetService) rather than its underlying ivar. You should only ever access the ivar directly in getters, setters, and init (also dealloc if aren't using ARC for some crazy reason).
You also should not call loadView yourself, rather just access the view property of the view controller. That will kick off the loading process and call viewDidLoad.
Also, if you're doing a lot of mocking, I highly recommend OCMock.
I have seen in the BNR 3rd edition an example to do a static singleton class.
To do that, they explain how to avoid a creation cycle calling the superclass alloc:
static MyClass *myclass = [[super alloc] init];
MyClass has its own init method.
NSObject -> MyClass
My doubt is: Which init class is sent? NSOject init, or MyClass init
Nested alloc init equals:
myclass = [super alloc] and then
myclass = [myclass init] ???????????
OR
myclass = [super alloc] and then myclass = [super init]
Do not use super, but do use self. Otherwise subclassing of your singleton will not work. The correct way is something like this:
+ (MyClass *)sharedInstance {
static MyClass *instance = nil;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
instance = [[self alloc] init];
});
return instance;
}
dispatch_once guarantees that your code (block in this case) is called only once. And self guarantees that subclassing will work properly.
for you question, the selector is always called on the subclass's implementation, which is your first guess
the way described in the book is a valid way to implement singleton, but i do not suggest it though. Robert Vojta's solution is good.
i cannot see how necessary to override allocWithZone, then you also need to make sure init does nothing (at least not leak)
Just for add some tests:
I have created 2 MyClass classes: NSObject -> Myclass -> My2ndClass
So:
#implementation Myclass
+(id) sharedClass {
static Myclass *miclase = nil;
miclase = [[self alloc] init];
NSLog(#"%#", [super description]);
return miclase;
}
-(id)init {
self = [super init];
NSLog(#"init de Myclass");
return self;
}
-(NSString *)description {
return #"i am Myclass";
}
#end
AND:
#implementation My2ndClass
+(id) sharedClass {
static My2ndClass *miclase = nil;
miclase = [[super alloc] init];
//miclase = [super init]; CRASH
NSLog(#"%#", [super description]);
return miclase;
}
-(id)init {
self = [super init];
NSLog(#"init de My2ndClass");
NSLog(#"%#", [super description]);
return self;
}
-(NSString *)description {
return #"i am My2ndClass";
}
#end
Then in AppDelegate:
Myclass *miclase = [Myclass sharedClass];
My2ndClass *mi2ndclase = [My2ndClass sharedClass];
This is the console output:
2012-09-03 17:18:55.742 Dynamic Typing[2891:207] init de Myclass
2012-09-03 17:18:55.744 Dynamic Typing[2891:207] Myclass
2012-09-03 17:18:55.746 Dynamic Typing[2891:207] init de Myclass
2012-09-03 17:18:55.747 Dynamic Typing[2891:207] init de My2ndClass
2012-09-03 17:18:55.748 Dynamic Typing[2891:207] i am Myclass
2012-09-03 17:18:55.751 Dynamic Typing[2891:207] My2ndClass
Like xlc0212 told, the correct messages when they are nested are:
miclase = [super alloc];
miclase = [miclase init];
Besides, if i do
miclase = [super alloc]
and then
miclase = [super init]
it CRASHES.
When is sent a class method (+) [super description], it logs class name (Myclass and My2ndClass). They are de class itself and don't have super object, do they?
- (BOOL)coolMethod:(NSString*)str
{
//do some stuff
Webservice *ws = [[WebService alloc] init];
NSString *result = [ws startSynchronous:url];
if ([result isEqual:#"Something"])
{
//More calculation
return YES;
}
return NO;
}
I am using OCUnit
In the following method how can i mock my WebService Object, or the result to the method "startSynchronous" to be able to write an independent unit test?
Is it possible to inject some code in there to either create a mock web service or return a mock data on startSynchronous call?
One way is to use categories and override methods you want, you can even override the init method to return a mock object:
#interface Webservice (Mock)
- (id)init;
#end
#implementation Webservice (Mock)
- (id)init
{
//WebServiceMock is a subclass of WebService
WebServiceMock *moc = [[WebServiceMock alloc] init];
return (Webservice*)moc;
}
#end
The problem with this is that if you want to make the object return different results in different tests in 1 test file you cannot do that. (You can override each method once per test page)
EDIT:
This is an old question I posted, I thought I would update the answer to how I write testable code and unit test it nowadays :)
ViewController Code
#implementation MyViewController
#synthesize webService;
- (void)viewDidLoad
{
[super viewDidLoad];
[self.webService sendSomeMessage:#"Some_Message"];
}
- (WebService *)webService
{
if (!_webService)
_webService = [[WebService alloc] init];
return _webService;
}
#end
Test Code
#implementation MyViewControllerTest
- (void)testCorrectMessageIsSentToServer
{
MyViewController *vc = [[MyViewController alloc] init];
vc.webService = [OCMock niceMockForClass:[WebService class]];
[[(OCMockObject *)vc.webService expect] sendSomeMessage#"Some_Message"];
[vc view]; /* triggers viewDidLoad */
[[(OCMockObject *)vc.webService verify];
}
#end
Building on top of the WebService answer from aryaxt, here's a little trick to be able to get different results in different test.
First, you need a singleton object which will be used to store the desired answer, right before the test
TestConfiguration.h
#import <Foundation/Foundation.h>
#import <objc/runtime.h>
#import <objc/message.h>
void MethodSwizzle(Class c, SEL orig, SEL new);
#interface TestConfiguration : NSObject
#property(nonatomic,strong) NSMutableDictionary *results;
+ (TestConfiguration *)sharedInstance;
-(void)setNextResult:(NSObject *)result
forCallToObject:(NSObject *)object
selector:(SEL)selector;
-(NSObject *)getResultForCallToObject:(NSObject *)object selector:(SEL)selector;
#end
TestConfiguration.m
#import "TestConfiguration.h"
void MethodSwizzle(Class c, SEL orig, SEL new) {
Method origMethod = class_getInstanceMethod(c, orig);
Method newMethod = class_getInstanceMethod(c, new);
if(class_addMethod(c, orig, method_getImplementation(newMethod), method_getTypeEncoding(newMethod)))
class_replaceMethod(c, new, method_getImplementation(origMethod), method_getTypeEncoding(origMethod));
else
method_exchangeImplementations(origMethod, newMethod);
};
#implementation TestConfiguration
- (id)init
{
self = [super init];
if (self) {
self.results = [[NSMutableDictionary alloc] init];
}
return self;
}
+ (TestConfiguration *)sharedInstance
{
static TestConfiguration *sharedInstance = nil;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
sharedInstance = [[TestConfiguration alloc] init];
// Do any other initialisation stuff here
});
return sharedInstance;
}
-(void)setNextResult:(NSObject *)result
forCallToObject:(NSObject *)object
selector:(SEL)selector
{
NSString *className = NSStringFromClass([object class]);
NSString *selectorName = NSStringFromSelector(selector);
[self.results setObject:result
forKey:[[className stringByAppendingString:#":"] stringByAppendingString:selectorName]];
}
-(NSObject *)getResultForCallToObject:(NSObject *)object selector:(SEL)selector
{
NSString *className = NSStringFromClass([object class]);
NSString *selectorName = NSStringFromSelector(selector);
return [self.results objectForKey:[[className stringByAppendingString:#":"] stringByAppendingString:selectorName]];
}
#end
Then you would define your "Mock" category to define mock methods , such as :
#import "MyWebService+Mock.h"
#import "TestConfiguration.h"
#implementation MyWebService (Mock)
-(void)mockFetchEntityWithId:(NSNumber *)entityId
success:(void (^)(Entity *entity))success
failure:(void (^)(NSError *error))failure
{
Entity *response = (Entity *)[[TestConfiguration sharedInstance] getResultForCallToObject:self selector:#selector(fetchEntityWithId:success:failure:)];
if (response == nil)
{
failure([NSError errorWithDomain:#"entity not found" code:1 userInfo:nil]);
}
else{
success(response);
}
}
#end
And finally, in the tests themselves, you would swizzle the mock method in the setup , and define the expected answer in each test, before the call
MyServiceTest.m
- (void)setUp
{
[super setUp];
//swizzle webservice method call to mock object call
MethodSwizzle([MyWebService class], #selector(fetchEntityWithId:success:failure:), #selector(mockFetchEntityWithId:success:failure:));
}
- (void)testWSMockedEntity
{
/* mock an entity response from the server */
[[TestConfiguration sharedInstance] setNextResult:[Entity entityWithId:1]
forCallToObject:[MyWebService sharedInstance]
selector:#selector(fetchEntityWithId:success:failure:)];
// now perform the call. You should be able to call STAssert in the blocks directly, since the success/error block should now be called completely synchronously.
}
Remark : in my example, the TestConfiguration uses class/selector as a key instead of object/selector. That means every object of the class will use the same answer for the selector. That is most likely your case, as webservice are often singleton. But it should be improved to an object/selector maybe using the objet's memory address instead of its class
If I create a custom initWith for an object do I essentially include the code I would add should I want to override init?
-(id) init {
self = [super init];
if (self) {
NSLog(#"_init: %#", self);
}
return(self);
}
e.g.
-(id) initWithX:(int) inPosX andY:(int) inPosY {
self = [super init];
if(self) {
NSLog(#"_init: %#", self);
posX = inPosX;
posY = inPosY;
}
return(self);
}
gary
You can create one designated initializer that accepts all parameters that you want to make available in initialization.
Then you call from your other -(id)init your designated initializer with proper parameters.
Only the designated initializer will initialize super class [super init].
Example:
- (id)init
{
return [self initWithX:defaultX andY:defaultY];
}
- (id)initWithPosition:(NSPoint)position
{
return [self initWithX:position.x andY:position.y];
}
- (id)initWithX:(int)inPosX andY:(int)inPosY
{
self = [super init];
if(self) {
NSLog(#"_init: %#", self);
posX = inPosX;
posY = inPosY;
}
return self;
}
The designated initializer is -(id)initWithX:andY: and you call it from other initializers.
In case you want to extend this class you call your designated initializer from subclass.
I'd suggest creating one main initializer that handles most of the work. You can then create any number of other initializers that all call this main one. The advantage of this is if you want to change the initialization process, you'll only have to change one spot. It might look like this:
-(id) initWithX:(float)x {
if (self = [super init]) {
/* do most of initialization */
self.xVal = x;
}
return self;
}
-(id) init {
return [self initWithX:0.0f];
}
In this example initWithX: is our main initializer. The other initializer (init) simply calls initWithX: with a default value (in this case 0).
Yes, that's exactly how I do it. One slight change will cut out a line of code:
if (self = [super init]) {
As opposed to:
self = [super init];
if(self) {
For modern Objective-C ...
UDFile.h
#import <Foundation/Foundation.h>
#interface UDFile : NSObject
#property (nonatomic, strong) NSString *name;
- (instancetype)initWithName:(NSString *)name NS_DESIGNATED_INITIALIZER;
#end
UDFile.m
#import "UDFile.h"
#implementation UDFile
- (instancetype)initWithName:(NSString *)name {
self = [super init];
if (self) {
_name = [name copy];
}
return self;
}
- (instancetype)init {
return [self initWithPathname:#""];
}
Sometimes, you want to reuse some initialisation code and modify the behaviour only slightly for specific initialisers. In this case, I do the following:
- (id) init
{
self = [super init];
if (!self) return nil;
// These values are always initialised this way
ivar1 = 10;
ivar2 = #"HellO";
ivar3 = [[NSMutableArray alloc] initWithCapacity:10];
ivar4 = 22;
return self;
}
- (id) initWithIvar4:(int) aValue
{
// call -init on self, which will call -init on super for us, and set
// up ivar1, ivar2, ivar3, and ivar4.
self = [self init];
if (!self) return nil;
// Change ivar4 from the default 22 to whatever aValue is.
ivar4 = aValue;
return self;
}