iOS 替代UDID解决方案－－UUID

#import <Foundation/Foundation.h>@interface UUID : NSObject{}@property (nonatomic, readonly, retain) NSString *UUIDString;+ (UUID *)sharedUUID;@end

#import "UUID.h"#define UUID_KEY (@"MobileUUID")static UUID *_sharedUUID = nil;@implementation UUID@synthesize UUIDString = _UUIDString;+ (UUID *)sharedUUID;{    @synchronized(self)    {        if(_sharedUUID == nil)        {            _sharedUUID = [[UUID alloc] init];        }    }    return _sharedUUID;}- (id)init{    if((self = [super init]))    {    }    return self;}#pragma mark -#pragma mark UUIDString- (NSString *)UUIDString{    NSString *uuidString = [[NSUserDefaults standardUserDefaults] objectForKey:UUID_KEY];        if(uuidString && [uuidString length])    {        return uuidString;    }    else    {           CFUUIDRef uuidRef = CFUUIDCreate(nil);        CFStringRef stringRef = CFUUIDCreateString(nil, uuidRef);        uuidString = (NSString *)CFStringCreateCopy(nil, stringRef);        CFRelease(uuidRef);        CFRelease(stringRef);                [[NSUserDefaults standardUserDefaults] setObject:uuidString forKey:UUID_KEY];        [[NSUserDefaults standardUserDefaults] synchronize];                 return [uuidString autorelease];    }        return nil;}#pragma mark -#pragma mark dealloc- (void)dealloc{    [_UUIDString release];    [_sharedUUID release];        [super dealloc];}@end