Single case Mode-ios

#import <Foundation/Foundation.h> @interface usercontext:nsobject <NSCopying> @property (nonatomic,copy) NSString *name; @property (nonatomic,copy) nsstring *emial;+ (id) shareusercontext; @end

#import "UserContext.h" static UserContext *segtoninstance=nil; @implementation usercontext+ (ID) shareusercontext{        @synchronized (self) {            if (segtoninstance==nil) {        segtoninstance=[[[self class] alloc] init];        }            }    return segtoninstance;} + (ID) allocwithzone: (struct _nszone *) zone{    if (segtoninstance==nil) {        segtoninstance=[super allocwithzone: Zone];    }    return segtoninstance;} -(ID) Copywithzone: (Nszone *) zone{        return segtoninstance;    } @end

/** single case mode ***/        UserContext *usercontext=[usercontext Shareusercontext];        UserContext *usercontext2=[usercontext Shareusercontext];        UserContext *usercontext3=[[usercontext alloc] init];        UserContext *usercontext4=[usercontext copy];        NSLog (@ "%p", usercontext);        NSLog (@ "%p", usercontext2);        NSLog (@ "%p", usercontext3);        NSLog (@ "%p", USERCONTEXT4);