singleton in objective c

Question

I saw a singleton example on objective-c book. However, I don\'t know if there is difference of meaning of \'singleton\' definition between objective-c and other langs. Can this

Answer 1

Singleton class is used to save the data for use anywhere in app.

//SingletonObject
#define saveDataSingletonObject ((SaveDataSingleton*)[SaveDataSingleton sharedManager])

@interface SaveDataSingleton : NSObject

@property (nonatomic,strong) NSMutableArray *DataArr;
+ (id)sharedManager;
-(void)clearAllSaveData;

@end

@implementation SaveDataSingleton
@synthesize DataArr;
+ (id)sharedManager {
    static SaveDataSingleton *sharedManager;
    if(!sharedManager) {
        @synchronized(sharedManager) {
            sharedManager = [SaveDataSingleton new];
        }
    }
    return sharedManager;
}
-(void)clearAllSaveData{
    DataArr=nil;
}
- (id)init {
    if (self = [super init]) {
        DataArr = [[NSMutableArray alloc]init];
    }
    return self;
}
// using setter getter save and retrieve data
+(void)setDataArr:(NSMutableArray *)Dataarr
{
    self.DataArr = [[NSMutableArray alloc]initWithArray:Dataarr];
}

+(NSMutableArray *)DataArr
{
    return self.DataArr;
}
@end

Save and Retrieve data // Use singleton Object

// save data using setter function.
[saveDataSingletonObject setDataArr:Array];
//fetch data using getter function.
NSArray *arr=[saveDataSingletonObject DataArr];