ok,腾讯面试:oc单例模式
static DataManager
* sharedDataManager
= nil;
+ (DataManager
* ) sharedManager
{
@synchronized(self)
{
if
(sharedDataManager ==
nil)
{
[[self alloc] init];
}
}
return
sharedDataManager;
}
+ (id)allocWithZone:(NSZone
* )zone
{
@synchronized(self)
{
if
(sharedDataManager ==
nil)
{
sharedDataManager =
[super allocWithZone:zone];
return
sharedDataManager;
}
}
return
nil;
}