objective-c : give object a unique numeric ID (itemId)

snippet.m

//give object a unique numeric ID (itemId)

//ChecklistItem.h
@property (nonatomic, assign) NSInteger itemId;

//ChecklistItem.m
//initWithCoder - for view controllers that are automatically loaded from a nib or Storyboard
//for unfreezing the objects from the file
- (id)initWithCoder:(NSCoder *)aDecoder
{
    if (debug==1) {NSLog(@"Running %@ '%@'", self.class, NSStringFromSelector(_cmd));}
    
    if ((self = [super init])) {
        //opposite from encodeWithCoder
        self.text = [aDecoder decodeObjectForKey:@"Text"];
        self.checked = [aDecoder decodeBoolForKey:@"Checked"];
        
        //for local notifications
        self.dueDate = [aDecoder decodeObjectForKey:@"DueDate"];
        self.shouldRemind = [aDecoder decodeBoolForKey:@"ShouldRemind"];
        self.itemId = [aDecoder decodeIntegerForKey:@"ItemID"];
        
    }
    return self;
}


#pragma mark - encode protocol

- (void)encodeWithCoder:(NSCoder *)aCoder
{
    if (debug==1) {NSLog(@"Running %@ '%@'", self.class, NSStringFromSelector(_cmd));}
    
    [aCoder encodeObject:self.text forKey:@"Text"];
    [aCoder encodeBool:self.checked forKey:@"Checked"];
    
    //for local notifications
    [aCoder encodeObject:self.dueDate forKey:@"DueDate"];
    [aCoder encodeBool:self.shouldRemind forKey:@"ShouldRemind"];
    [aCoder encodeInteger:self.itemId forKey:@"ItemID"];
    
}


#import "DataModel.h"

#pragma mark - 초기화

- (id)init {
    if (debug==1) {NSLog(@"Running %@ '%@'", self.class, NSStringFromSelector(_cmd));}
    
    if (self = [super init]) {
        
        self.itemId = [DataModel nextChecklistItemId];
    }
    return self;
}


//DataModel.h
//class method
+ (NSInteger)nextChecklistItemId;

//DataModel.m
#pragma mark - for local notifications

+ (int)nextChecklistItemId {
    
    NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];
    NSInteger itemId = [userDefaults integerForKey:@"ChecklistItemId"];
    [userDefaults setInteger:itemId + 1 forKey:@"ChecklistItemId"];
    
    [userDefaults synchronize]; //force NSUserDefaults to write changes to disk immediately
    
    return itemId;
}


#pragma mark - register Defaults Value for NSUserDefaults

- (void)registerDefaults
{
    if (debug==1) {NSLog(@"Running %@ '%@'", self.class, NSStringFromSelector(_cmd));}
    
    //register Defaults Value for NSUserDefaults
    NSDictionary *dictionary = @{ @"ChecklistIndex" : @-1,
                                  @"FirstTime" : @YES,
                                  @"ChecklistItemId" : @0, //Add a default value for “ChecklistItemId”
                                  };
    
    [[NSUserDefaults standardUserDefaults] registerDefaults:dictionary];
}


//ChecklistViewController.m
- (void)configureTextForCell:(UITableViewCell *)cell withChecklistItem:(ChecklistItem *)item
{
    if (debug==1) {NSLog(@"Running %@ '%@'", self.class, NSStringFromSelector(_cmd));}
    
    UILabel *label = (UILabel *)[cell viewWithTag:1000]; //tag can get a reference to a control without making @property
    
    //label.text = item.text;
    
    //to test itemId
    label.text = [NSString stringWithFormat:@"%d: %@", item.itemId, item.text]; //test ChecklistItemId
}