ARC下基础写法:
static AudioTool *instance;
+ (instancetype)sharedAudioTool{
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
instance = [[AudioTool alloc] init];
});
return instance;
}
注意:由于viewController.m中alloc和shared调用的顺序不一样,所以后面的实现方法里面都重写一下dispatch_once,但是copy是对象copy,所以不用重写
+ (instancetype)allocWithZone:(struct _NSZone *)zone{
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
instance = [super allocWithZone:zone];
});
return instance;
}
- (id)copyWithZone:(NSZone *)zone{
return instance;
}
MRC下除上面三个方法外,还要多写四个方法
-(oneway void)release{
//不做事情
}
-(instancetype)retain{
return instance;
}
-(NSUInteger)retainCount{
return 1;
}
- (instancetype)autorelease{
return instance;
}
