單例模式Singleton-OC版

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代碼-.h檔案：

#import <Foundation/Foundation.h>@interface Instance : NSObject+ (instancetype)sharedInstance;@end

 

代碼-.m檔案：

#import "Instance.h"@implementation Instancestatic id _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;}- (id)mutableCopyWithZone:(NSZone *)zone {    return _instance;}@end

 

單例模式Singleton-OC版