[obj-c] Singleton(单例) for object-c

如何使用obj-c实践singleton(单例)

MySingleton.h

#import <Foundation/Foundation.h> @interface MySingleton : NSObject { }+(MySingleton*)sharedMySingleton;-(void)test;@end

MySingleton.m

@implementation MySingletonstatic MySingleton* _sharedMySingleton = nil; +(MySingleton*)sharedMySingleton{@synchronized([MySingleton class]){if (!_sharedMySingleton)[[self alloc] init]; return _sharedMySingleton;} return nil;} +(id)alloc{@synchronized([MySingleton class]){NSAssert(_sharedMySingleton == nil, @"Attempted to allocate a second instance of a singleton.");_sharedMySingleton = [super alloc];return _sharedMySingleton;} return nil;} -(id)init {self = [super init];if (self != nil) {// initialize stuff here} return self;} -(void)test {NSLog(@"Hello World!");}@end