CODEWITHSUNDEEP
objective-calloc
Christopher Palmer
Christopher Palmer

Reputation: 3

Working with Class, properties and initialization

I'm working on this assignment I found online (Intermediate App Development Using iOS). I'm stuck on part c and d, don't know exactly what its asking me to do. I know how to print int (%i) and object (%@), but %@ print all data? Any help or suggestion will be appreciated.

Part 6

a) Implement class A with properties a1, a2, and a3 (int, string, int).
b) New objects are automatically initialized to 1, "hello", 1
c) Also provide initializer to any data and constructor (called without alloc) to do the same.
d) Make sure %@ object of A will print all data.

Here is what I have done so far: 

// classA.h
#import <Foundation/Foundation.h>

@interface ClassA : NSObject
// Part 6a
@property int a1;
@property NSString *a2;
@property int a3;

-(ClassA *) initWithA1: (int) x andA2: (NSString *) s andA3: (int) y;
@end

//classA.m
#import "ClassA.h"

@implementation ClassA

-(ClassA *) initWithA1:(int)x andA2:(NSString *)s andA3:(int)y {
    self = [super init];
    if (self) {
        self.a1 = x;
        self.a2 = s;
        self.a3 = y;
    }
    return self;
}

// part 6b
-(ClassA *) init {
    if (self = [super init]) {
        self.a1 = 0;
        self.a2 =@"hello";
        self.a3 = 0;
    }
    return self;
}
@end

Upvotes: 0

Views: 118

Answers (2)

Sviatoslav Yakymiv
Sviatoslav Yakymiv

Reputation: 7935

As @orbitor wrote, your class should have one designated initialiser.

So, your init method should probably read something like:

- (id) init
{
    return [self initWithA1:1 andA2:@"hello" andA3:1];
}

In order to print all object you should implement custom description method:

- (NSString *) description
{
    return [NSString stringWithFormat:@"a1 = %d, a2 = %@, a3 = %d", self.a1, self.a2, self.a3];;
}

According to c: Class method new just calls alloc and init methods so you should only make sure that you wrote properly all initialisers.

Upvotes: 0

orbitor
orbitor

Reputation: 93

In reference to part "b" of your question:

As a general rule, only 1 initializer should be doing the "real" work. This is often referred to as the designated initializer. So, your init method should probably read something like:

- (id) init
{
    return [self initWithA1:1 andA2:@"hello" andA3:1];
}

Upvotes: 1

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