Objective-Cでシングルトン

singleton.m

#import "Status.h"

@implementation Status

@synthesize customUrlAlbumId = _customUrlAlbumId;
@synthesize isTopReload = _isTopReload;
@synthesize isThumbnailReload = _isThumbnailReload;
@synthesize isInvitationReload = _isInvitationReload;

static Status *sharedHistory = nil;

+ (Status *)sharedManager {
    @synchronized (self) {
        if (sharedHistory == nil) {
            sharedHistory = [[self alloc] init];
        }
    }
    return sharedHistory;
}

+ (id)allocWithZone:(NSZone *)zone {
    @synchronized (self) {
        if (sharedHistory == nil) {
            sharedHistory = (Status *) [super allocWithZone:zone];
            return sharedHistory;
        }
    }
    return nil;
}

- (id)copyWithZone:(NSZone *)zone {
    return self;  // シングルトン状態を保持するため何もせず self を返す
}

@end