#import <Foundation/Foundation.h>
@interface Instance : NSObject
+ (instancetype)sharedInstance;
@end
@implementation Instance
static Instance *instance;
+ (instancetype)allocWithZone:(struct _NSZone *)zone
{
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
instance = [super allocWithZone:zone];
});
return instance;
}
+ (instancetype)sharedInstance
{
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
instance = [[self alloc] init];
});
return instance;
}
- (id)copyWithZone:(NSZone *)zone
{
return instance;
}
@end
@implementation Instance
static Instance *instance;
+ (instancetype)allocWithZone:(struct _NSZone *)zone
{
@synchronized(self) {
if (instance == nil) {
instance = [super allocWithZone:zone];
}
}
return instance;
}
+ (instancetype)sharedInstance
{
@synchronized(self) {
if (instance == nil) {
instance = [[self alloc] init];
}
}
return instance;
}
- (id)copyWithZone:(NSZone *)zone
{
return instance;
}
@end
最后編輯于 ：
?著作權(quán)歸作者所有,轉(zhuǎn)載或內(nèi)容合作請聯(lián)系作者
