Creating an Object - Objective-C

Question

Problem

I am trying to create an object in Objective-C. I know how to do it but I have a few questions regarding the methods in the implementation file.

The Object:

@interface Program : NSObject {
    NSString *sid;
    NSString *le;
    NSString *sd;
    NSString *pid;
    NSString *n;
    NSString *d;
    NSString *url;
}

@property (nonatomic, retain) NSString *sid;
@property (nonatomic, retain) NSString *le;
@property (nonatomic, retain) NSString *sd;
@property (nonatomic, retain) NSString *pid;
@property (nonatomic, retain) NSString *n;
@property (nonatomic, retain) NSString *d;
@property (nonatomic, retain) NSString *url;

@end

Question

I should only implement dealloc and init.. Am I right on this?

Furthermore, I have no special initializations, so should I keep the default init method as follows?

- (id)init
{
    self = [super init];
    if (self) {
        // Initialization code here.
    }

    return self;
}

Are you sure you want to retain the NSStrings? If a retained object is actually an NSMutableString, it can change from under you. I find it rare to retain NSString properties; I usually copy them. — Richard
– Richard, Commented Aug 5, 2011 at 16:01
Agreed. Everything I've read says to use copy for NSStrings. — John T
– John T, Commented Aug 5, 2011 at 16:10

taskinoor · Accepted Answer · 2011-08-05 15:58:35Z

5

You need to synthesize the properties and if you don't need any custom initialization then you can keep the init method as it is. In fact there is no need to implement init here. But in dealloc you need to release the strings.

@implementation Program

@synthesize sid;
// ... synthesize others

- (void)dealloc {
    [sid release];
    // ... release others

    [super dealloc];
}

@end

edited Aug 5, 2011 at 15:58

answered Aug 5, 2011 at 15:52

taskinoor

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Comments

John T · Accepted Answer · 2011-08-05 15:50:02Z

3

I may be wrong, and I'm sure someone will correct me ;), but if you're not doing any special initializations, you don't need the init method.

answered Aug 5, 2011 at 15:50

John T

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Comments

JeremyP · Accepted Answer · 2011-08-05 15:51:39Z

1

I should only implement dealloc and init.. Am I right on this?

You need to also implement all those properties, but you can make the compiler do all the hard work by @synthesizeing them.

Each of the properties needs to be released in your -dealloc

answered Aug 5, 2011 at 15:51

JeremyP

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Comments

Praveen-K · Accepted Answer · 2011-08-05 16:41:35Z

if you are creating a properties (you should synthesize so the compiler will automatically generate getter and setter methods for us), and if you are doing custom initialization then you need to remember self keyword

-(id)init{
  self.sid = @"SID" //Without the self object & the dot we are no longer sending 
                     //an object a message but directly accessing ivar named sid
 }

 - (void)dealloc {
     self.sid = nil;
     [super dealloc];
   }

Colin · Accepted Answer · 2011-08-05 15:53:08Z

0

You do need to implement dealloc, and release all of your ivars. Also, don't forget to @synthesize your properties!

answered Aug 5, 2011 at 15:53

Colin

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Comments

taskinoor · Accepted Answer · 2011-08-05 16:05:20Z

0

You only need to implement - dealloc and - init if you have tear-down or setup to do. If you have none, you don't have to implement either because the defaults inherited from NSObject do the job.

edited Aug 5, 2011 at 16:05

taskinoor

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answered Aug 5, 2011 at 15:50

Ryan Ballantyne

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