| 一、ARC下的單例實現(xiàn) |
說明：在用戶實例化的方法控制單次執(zhí)行，同時開放單例的初始化方法。
-(instancetype)init{ self=[super init]; if(self){ static dispatch_once_t onceToken; dispatch_once(&onceToken, ^{ }); } return self; }static id instance; +(instancetype)allocWithZone:(struct _NSZone *)zone{ static dispatch_once_t onceToken; dispatch_once(&onceToken, ^{ instance=[super allocWithZone:zone]; }); return instance;} + (instancetype) shareAudio{ static dispatch_once_t onceToken; dispatch_once(&onceToken, ^{ instance=[[self alloc]init]; }); return instance; } +(id)copyWithZone:(struct _NSZone *)zone{ return instance;}
| 二、MRC下的單例實現(xiàn) |
說明：在用戶實例化的方法控制單次執(zhí)行，同時開放單例的初始化方法,由于當前為MRC所以需要控制參內(nèi)存管理的方法單次執(zhí)行，因此相比ARC需要增加：
static id instance; +(instancetype)allocWithZone:(struct _NSZone *)zone{ static dispatch_once_t onceToken; dispatch_once(&onceToken, ^{ instance=[super allocWithZone:zone]; }); return instance; } + (instancetype) shareAudio{ static dispatch_once_t onceToken; dispatch_once(&onceToken, ^{ instance=[[self alloc]init]; }); return instance; } -(oneway void)release{ } -(instancetype)autorelease{ return instance; } -(instancetype)retain{ return instance; } -(NSUInteger)retainCount{ return 1; }
| 三、兼容MRC 和ARC的宏定義 |
說明：為了方便后期的引用，可以將單例抽取為宏定義，鑒于抽取的時候考慮到當前的手動計數(shù)和自動計數(shù)因此引入條件編譯：
#if !__has_feature(objc_arc)======當前是ARC#else======當前是MRC#endif代碼：#define singleton_h(name) + (instancetype) share##name;#if !__has_feature(objc_arc)#define singleton_m(name)/ static id instance;/+(instancetype)allocWithZone:(struct _NSZone *)zone{/ static dispatch_once_t onceToken;/ dispatch_once(&onceToken, ^{/ instance=[super allocWithZone:zone];/ });/ return instance;/}///+ (instancetype) share##name{/ static dispatch_once_t onceToken;/ dispatch_once(&onceToken, ^{/ instance=[[self alloc]init];/ });/ return instance;/}/-(oneway void)release{/}//-(instancetype)autorelease{/ return instance;/}//-(instancetype)retain{/ return instance;/}//+(id)copyWithZone:(struct _NSZone *)zone{/ return instance;/}/-(NSUInteger)retainCount{/ return 1;/}#else#define singleton_m(name)/static id instance;/+(instancetype)allocWithZone:(struct _NSZone *)zone{/ static dispatch_once_t onceToken;/ dispatch_once(&onceToken, ^{/ instance=[super allocWithZone:zone];/});/ return instance;/}///+ (instancetype) share##name{/ static dispatch_once_t onceToken;/ dispatch_once(&onceToken, ^{/ instance=[[self alloc]init];/ });/ return instance;/}//+(id)copyWithZone:(struct _NSZone *)zone{/ return instance;/}#endif
| 四、文件引用 |
1 在.h文件引用singleton_h(audio);
2 在.m文件引用singleton_m(audio);
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