New a better way of initializing classes and objects - iphone

Question

Here is a code that I thought of to initialize my picker with. Is there a better way to write this?
The interface
#interface roomsClass : NSObject {
NSInteger roomID;
NSString *name;
NSString *desc;
}
#property (nonatomic, readwrite) NSInteger roomID;
#property (nonatomic, copy) NSString *name;
#property (nonatomic, copy) NSString *desc;
#end
#interface typesClass : NSObject {
NSInteger typeID;
NSString *name;
}
#property (nonatomic, readwrite) NSInteger typeID;
#property (nonatomic, copy) NSString *name;
#end
The implementation
NSMutableArray *tempArrayA = [[NSMutableArray alloc] init];
self.roomsArray = tempArrayA;
[tempArrayA release];
roomsClass *tempObjA1 = [[roomsClass alloc] init];
tempObjA1.roomID = 202;
tempObjA1.name = #"MH202";
tempObjA1.desc = #"Lab";
[roomsArray addObject:tempObjA1];
[tempObjA1 release];
roomsClass *tempObjA2 = [[roomsClass alloc] init];
tempObjA2.roomID = 207;
tempObjA2.name = #"MH207";
tempObjA2.desc = #"Office";
[roomsArray addObject:tempObjA2];
[tempObjA2 release];
roomsClass *tempObjA3 = [[roomsClass alloc] init];
tempObjA3.roomID = 208;
tempObjA3.name = #"MH208";
tempObjA3.desc = #"Office";
[roomsArray addObject:tempObjA3];
[tempObjA3 release];
roomsClass *tempObjA4 = [[roomsClass alloc] init];
tempObjA4.roomID = 209;
tempObjA4.name = #"MH209";
tempObjA4.desc = #"Lab";
[roomsArray addObject:tempObjA4];
[tempObjA4 release];
roomsClass *tempObjA5 = [[roomsClass alloc] init];
tempObjA5.roomID = 210;
tempObjA5.name = #"MH210";
tempObjA5.desc = #"Lab";
[roomsArray addObject:tempObjA5];
[tempObjA5 release];
roomsClass *tempObjA6 = [[roomsClass alloc] init];
tempObjA6.roomID = 211;
tempObjA6.name = #"MH211";
tempObjA6.desc = #"Office";
[roomsArray addObject:tempObjA6];
[tempObjA6 release];
NSMutableArray *tempArrayB = [[NSMutableArray alloc] init];
self.typesArray = tempArrayB;
[tempArrayB release];
typesClass *tempObjB1 = [[typesClass alloc] init];
tempObjB1.typeID = 1;
tempObjB1.name = #"Desktop";
[typesArray addObject:tempObjB1];
[tempObjB1 release];
typesClass *tempObjB2 = [[typesClass alloc] init];
tempObjB2.typeID = 2;
tempObjB2.name = #"Laptop";
[typesArray addObject:tempObjB2];
[tempObjB2 release];
typesClass *tempObjB3 = [[typesClass alloc] init];
tempObjB3.typeID = 3;
tempObjB3.name = #"Monitor";
[typesArray addObject:tempObjB3];
[tempObjB3 release];
typesClass *tempObjB4 = [[typesClass alloc] init];
tempObjB4.typeID = 4;
tempObjB4.name = #"Server";
[typesArray addObject:tempObjB4];
[tempObjB4 release];
typesClass *tempObjB5 = [[typesClass alloc] init];
tempObjB5.typeID = 5;
tempObjB5.name = #"Printer";
[typesArray addObject:tempObjB5];
[tempObjB5 release];
typesClass *tempObjB6 = [[typesClass alloc] init];
tempObjB6.typeID = 6;
tempObjB6.name = #"Projector";
[typesArray addObject:tempObjB6];
[tempObjB6 release];
typesClass *tempObjB7 = [[typesClass alloc] init];
tempObjB7.typeID = 7;
tempObjB7.name = #"Other";
[typesArray addObject:tempObjB7];
[tempObjB7 release];
if (roomPicker == nil) {
roomPicker = [[UIPickerView alloc] initWithFrame:CGRectZero];
roomPicker.delegate = self;
roomPicker.dataSource = self;
roomPicker.showsSelectionIndicator = YES;
roomPicker.transform = CGAffineTransformMakeScale(1.0, 1.0);
roomPicker.tag = kRoomPicker;
}
txtRoomID.inputView = roomPicker;
if (typePicker == nil) {
typePicker = [[UIPickerView alloc] initWithFrame:CGRectZero];
typePicker.delegate = self;
typePicker.dataSource = self;
typePicker.showsSelectionIndicator = YES;
typePicker.transform = CGAffineTransformMakeScale(1.0, 1.0);
typePicker.tag = kTypePicker;
}
txtTypeID.inputView = typePicker;
The idea is to have the picker show some text, but when the user selects the text on the UIPickerView, the integer value/id of the selection be placed in the UITextField, rather than the text the user sees.
I am using iOS 4.3.1 on the device, with 4.3 SDK, and Xcode 3.2.6.

Answer 1

one way to reduce the redundancy is called a convenience constructor. a partial implementation is illustrated below:
#interface MONRoomsClass : NSObject {
NSInteger roomID;
NSString *name;
NSString *desc;
}
#property (nonatomic, readwrite) NSInteger roomID;
#property (nonatomic, copy) NSString *name;
/* note: ivar would normally be named 'description' */
#property (nonatomic, copy) NSString *desc;
/* designated initializer */
- (id)initWithRoomID:(NSInteger)inRoomID
name:(NSString *)inName
desc:(NSString *)inDesc;
/* convenience constructor */
+ (MONRoomsClass *)newRoomsClassWithRoomID:(NSInteger)inRoomID
name:(NSString *)inName
desc:(NSString *)inDesc;
/* convenience constructor */
+ (MONRoomsClass *)roomsClassWithRoomID:(NSInteger)inRoomID
name:(NSString *)inName
desc:(NSString *)inDesc;
#end
#implementation MONRoomsClass
- (id)initWithRoomID:(NSInteger)inRoomID
name:(NSString *)inName
desc:(NSString *)inDesc
{
/* error checking omitted */
self = [super init];
if (0 != self) {
roomID = inRoomID;
name = [inName copy];
desc = [inDesc copy];
}
return self;
}
+ (MONRoomsClass *)newRoomsClassWithRoomID:(NSInteger)inRoomID
name:(NSString *)inName
desc:(NSString *)inDesc
{
return [[self alloc] initWithRoomID:inRoomID name:[inName desc:inDesc];
}
+ (MONRoomsClass *)roomsClassWithRoomID:(NSInteger)inRoomID
name:(NSString *)inName
desc:(NSString *)inDesc
{
return [[[self alloc] initWithRoomID:inRoomID
name:inName
desc:inDesc] autorelease];
}
#end
void in_use() {
/* ... */
MONRoomsClass * roomsClass =
[MONRoomsClass newRoomsClassWithRoomID:210
name:#"MH210"
desc:#"Lab"];
[roomsArray addObject:roomsClass];
/* or */
[roomsArray addObject:
[[MONRoomsClass newRoomsClassWithRoomID:210
name:#"MH210"
desc:#"Lab"]
autorelease]];
/* or */
[roomsArray addObject:
[MONRoomsClass roomsClassWithRoomID:210
name:#"MH210"
desc:#"Lab"]];
/* ... */
}

Answer 2

There are a few possibilities for rewriting your array initialisation code. One that comes to mind is:
NSInteger roomIDs[] = { 202, 207, 208, 209, 210, 211 };
NSString *roomNames[] = { #"MH202", #"MH207", #"MH208", #"MH209", #"MH210", #"MH211" };
NSString *roomDescs[] = { #"Office", #"Lab", #"Office", #"Lab", #"Lab", #"Office" };
NSUInteger numberOfRooms = sizeof(roomIDs) / sizeof(NSInteger);
self.roomsArray = [NSMutableArray arrayWithCapacity:numberOfRooms];
for (int i = 0; i < numberOfRooms; i++) {
roomsClass *room = [[[roomsClass alloc] init] autorelease];
room.roomID = roomIDs[i];
room.name = roomNames[i];
room.desc = roomDescs[i];
[self.roomsArray addObject:room];
}
or
typedef struct {
NSInteger roomId;
NSString *name;
NSString *desc;
} RoomData;
RoomData rooms[] = {
{ 202, #"MH202", #"Office" },
{ 207, #"MH207", #"Lab" },
{ 208, #"MH208", #"Office" },
{ 209, #"MH209", #"Lab" },
{ 210, #"MH210", #"Lab" },
{ 211, #"MH211", #"Office" }
};
NSUInteger numberOfRooms = sizeof(rooms) / sizeof(RoomData);
self.roomsArray = [NSMutableArray arrayWithCapacity:numberOfRooms];
for (int i = 0; i < numberOfRooms; i++) {
roomsClass *room = [[[roomsClass alloc] init] autorelease];
room.roomID = rooms[i].roomId;
room.name = rooms[i].name;
room.desc = rooms[i].desc;
[self.roomsArray addObject:room];
}
If you couple those with #Justin’s convenience constructor, the for loop can be simplified to:
for (int i = 0; i < numberOfRooms; i++) {
[self.roomsArray addObject:[roomsClassWithRoomID:roomIDS[i]
name:roomNames[i]
desc:roomDescs[i]]];
}
or
for (int i = 0; i < numberOfRooms; i++) {
[self.roomsArray addObject:[roomsClassWithRoomID:rooms[i].roomId
name:rooms[i].name
desc:rooms[i].desc]];
}