1.最基本的寫法
+ (Singleton *)defaultSingleton
{
static Singleton *singleton = nil;
if (singleton == nil) {
singleton = [[Singleton alloc] init];
[singleton loadData];
}
return singleton;
}
2.上鎖
+ (Singleton *)defaultSingleton
{
@synchronized(self)
{
static Singleton *singleton = nil;
if (singleton == nil) {
singleton = [[Singleton alloc] init];
}
return singleton;
}
}
3.GCD寫法
+ (Singleton *)defaultSingleton
{
static Singleton *singleton = nil;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
singleton = [[Singleton alloc] init];
});
return singleton;
}