Objective C enumeration type in object changing on reassignment - objective-c

Question

I have searched and can't find the assert to this. I know it must be a fundamental thing I'm missing here.
I have an enum:
typedef enum {
NINETYBEND, NINETYBEND_FAST, NINETYBEND_SLOW, STRAIGHT
} BlockTypeEnum;
I am trying to use these values in objects I am creating like this:
BlockTypeEnum blockType = STRAIGHT;
XMLLevelPiece* piece = [[XMLLevelPiece alloc] init];
[piece initPiece:blockType];
My problem occurs when I try to use the same variable twice. If I create one object with an enum, change the enum and then create a second object using it, the enum in my first object changes to the second enum value. This is not what I want. Example below:
BlockTypeEnum blockType = STRAIGHT;
XMLLevelPiece* piece = [[XMLLevelPiece alloc] init];
[piece initPiece:blockType];
blockType = NINETYBEND_FAST;
XMLLevelPiece* piece2 = [[XMLLevelPiece alloc] init];
[piece2 initPiece:blockType];
NSLog([NSString stringWithFormat:#"%d", [piece getBlockType]]);
NSLog([NSString stringWithFormat:#"%d", [piece2 getBlockType]]);
//BOTH BLOCK TYPES ARE NOW NINETYBEND_FAST, NOT WHAT I WANTED!!
As far as I understood, an enum is just a glorified int, not a pointer, and I am reassigning the variable after adding to the first object. Please can someone tell me what I'm missing! Thanks very much, Simon.
Here is my code for XMLPiece, thanks!
#import "XMLLevelPiece.h"
#import "BlockType.h"
#import "GridCord.h"
#import "BlockColor.h"
#implementation XMLLevelPiece
BlockTypeEnum mBlockType;
BlockColorEnum mBlockColor;
int mRotation;
GridCord* mGridCords;
BlockColorEnum mLeftColor;
BlockColorEnum mTopColor;
BlockColorEnum mRightColor;
Boolean mRotatable;
Boolean mMoveable;
int mGroupID;
-(id) init
{
if( (self=[super init])) {
}
return self;
}
-(void)initPiece:(BlockTypeEnum)pBlockType pBlockColor:(BlockColorEnum)pBlockColor pRotation:(int)pRotation pGridCords:(GridCord*)pGridCords pLeftColor:(BlockColorEnum) pLeftColor pTopColor:(BlockColorEnum) pTopColor pRightColor:(BlockColorEnum) pRightColor pRotatable:(Boolean) pRotatable pMoveable:(Boolean) pMoveable pGroupID:(int) pGroupID
{
mBlockType = pBlockType;
mBlockColor = pBlockColor;
mRotation = pRotation;
mGridCords = pGridCords;
mLeftColor = pLeftColor;
mTopColor = pTopColor;
mRightColor = pRightColor;
mRotatable = pRotatable;
mMoveable = pMoveable;
mGroupID = pGroupID;
}
-(void)initPiece2
{
NSLog(#"poo");
}
-(Boolean)getRotatable
{
return mRotatable;
}
-(Boolean)getMoveable
{
return mMoveable;
}
-(int) getGroupID
{
return mGroupID;
}
-(BlockColorEnum) getLeftColor
{
return mLeftColor;
}
-(BlockColorEnum) getTopColor
{
return mTopColor;
}
-(BlockColorEnum) getRightColor
{
return mRightColor;
}
-(BlockTypeEnum) getBlockType
{
return mBlockType;
}
-(BlockColorEnum) getBlockColor
{
return mBlockColor;
}
-(int) getRotation
{
return mRotation;
}
-(id) getGridCords
{
return mGridCords;
}
-(void) setRotatable:(Boolean) pRotatable
{
mRotatable = pRotatable;
}
-(void) setMoveable:(Boolean) pMoveable
{
mMoveable = pMoveable;
}
#end

Answer 1

TL;DR
The answer is - that is not how you define ivars in Objective-C. I'm not even sure how that is supposed to behave but I can reproduce the error if I code it the same as you have.
I'd be interested for someone with more knowledge to explain what the behaviour/scope of those variable should be when they are defined like you have.
There's a lot of flaws in that code
You have not actually shown an initPiece:.
The long init... with all the arguments is likely a bad idea. Generally only add things to an init as either a convenience or if the object simply cannot function without it.
The use of get is not really correct in Objective-C
The class should potentially be defined more like
XMLLevelPiece.h
// You will need to import the header with the BlockTypeEnum defined
#interface XMLLevelPiece : NSObject
#property (nonatomic, assign) BlockTypeEnum blockType;
// .. Other properties
- (id)initWithPiece:(BlockTypeEnum)blockType; // I'm not so sure you need this
#end
XMLLevelPiece.m
#import "XMLLevelPiece.h"
#import "BlockType.h"
#import "GridCord.h"
#import "BlockColor.h"
#implementation XMLLevelPiece
#synthesize blockType = mBlockType;
- (id)initWithPiece:(BlockTypeEnum)blockType;
{
self = [super init];
if (self) {
mBlockType = blockType;
}
return self;
}
#end
Then you can use it like
BlockTypeEnum blockType = STRAIGHT;
XMLLevelPiece *p1 = [[XMLLevelPiece alloc] initWithPiece:blockType];
blockType = NINETYBEND_FAST;
XMLLevelPiece *p2 = [[XMLLevelPiece alloc] initWithPiece:blockType];
NSLog(#"%d", p1.blockType);
NSLog(#"%d", p2.blockType);
Which for me results in:
2012-01-08 15:29:31.782 Untitled[1297:707] 3
2012-01-08 15:29:31.791 Untitled[1297:707] 1
Optional observations
If you can do away with the dedicated initializer, the usage would look more like:
BlockTypeEnum blockType = STRAIGHT;
XMLLevelPiece *p1 = [[XMLLevelPiece alloc] init];
p1.blockType = blockType;
// all other assignments
blockType = NINETYBEND_FAST;
XMLLevelPiece *p2 = [[XMLLevelPiece alloc] init];
p2.blockType = blockType;
// all other assignments
NSLog(#"%d", p1.blockType);
NSLog(#"%d", p2.blockType);
To remove a couple of superflous lines you could remove the local blockType variable and assign the value straight to the object:
XMLLevelPiece *p1 = [[XMLLevelPiece alloc] init];
p1.blockType = STRAIGHT;

Answer 2

Your method call to initWithPiece does not match the definition.
Call:
[piece initPiece:blockType];
Definition:
-(void)initPiece:(BlockTypeEnum)pBlockType pBlockColor:(BlockColorEnum)pBlockColor pRotation:(int)pRotation pGridCords:(GridCord*)pGridCords pLeftColor:(BlockColorEnum) pLeftColor pTopColor:(BlockColorEnum) pTopColor pRightColor:(BlockColorEnum) pRightColor pRotatable:(Boolean) pRotatable pMoveable:(Boolean) pMoveable pGroupID:(int) pGroupID
Comments:
In general method calls with more than a few parameters are best a poor idea. Probably better in this case is using individual setters.
The convention in Objective-C as per Apple is to name getters without the "get" prefix. In fact a get prefix signifies a value returned via a reference parameter, not as the return result. Such usage will confuse the Analyzer and cause problems if using ARC.