SingleClass.m
#import <Foundation/Foundation.h>
@class SingleClass; static SingleClass *instance = nil; @interface SingleClass : NSObject <NSCopying>
+ (instancetype)shareInstance;
@end @implementation SingleClass
//类方法,获取单例对象
+ (instancetype)shareInstance{
if (!instance) {
instance = [[self alloc] init];
}
return instance;
}
//类方法,调用对象的alloc方法时返回已存在的单例
+ (instancetype)allocWithZone:(struct _NSZone *)zone{
if (!instance) {
instance = [super allocWithZone:zone];
}
return instance;
}
//copy时,返回已存在的单例
- (id)copyWithZone:(NSZone *)zone{
return instance;
}
//copy时,返回已存在的单例
- (id)copy{
return instance;
}
@end
main.m
int main(int argc, const char * argv[]) {
@autoreleasepool {
SingleClass *s1 = [SingleClass shareInstance];
SingleClass *s2 = [SingleClass shareInstance];
SingleClass *s3 = [[SingleClass alloc] init];
SingleClass *s4 = [s1 copy]; NSLog(@"%p",s1);
NSLog(@"%p",s2);
NSLog(@"%p",s3);
NSLog(@"%p",s4);
}
return ;
}
结果:
-- ::21.201 SingleDemo[:] 0x1001066e0
-- ::21.202 SingleDemo[:] 0x1001066e0
-- ::21.202 SingleDemo[:] 0x1001066e0
-- ::21.202 SingleDemo[:] 0x1001066e0