#import "SingleInstance.h"

@interface SingleInstance ()<NSCopying,NSMutableCopying>

@end

//定義一個當前單例物件的一個例項，並賦值為nil
static SingleInstance *instance = nil;

@implementation SingleInstance
+ (instancetype)sharedInstance
{
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        instance = [[self alloc] init];
    });

    return
 
 instance;
}
/**************真正的單例需過載所有和建立有關的方法**************/
//alloc會觸發，防止通過alloc建立一個不同的例項
+ (instancetype)allocWithZone:(struct _NSZone *)zone
{
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        instance = [super allocWithZone:zone];
    });

    return instance;
}

- (id)copyWithZone:(nullable NSZone *)zone
{
    return
 
 self;
}
- (id)mutableCopyWithZone:(nullable NSZone *)zone
{
    return self;
}

/**************手動記憶體管理需做的操作**************/

- (instancetype)retain
{
    return self;
}

- (oneway void)release
{

}

- (instancetype)autorelease
{
    return self;
}
- (NSUInteger)retainCount
{
    return MAXFLOAT;
}

- (void
 
)dealloc
{

}
@end