单例

PBShareData.h

@interface PBShareData : NSObject

+ (PBShareData *)shareData;

@end

PBShareData.m

@implementation PBShareData

+(PBShareData *)shareData
{
    static PBShareData *shareData = nil;
    static dispatch_once_t oneToken;
    dispatch_once(&oneToken, ^{
        shareData = [[PBShareData alloc]init];
    });
    return  shareData;
}

@end