实验证明：Objective-C++ 完美支持 ARC-白红宇

实验证明：Objective-C++ 完美支持 ARC

阅读量：6809 次

发布时间：2019-06-26

本文共 4759 字，大约阅读时间需要 15 分钟。

　　从 XCode 4.2 开始 Objective-C 支持 ARC，对于广大 iPone 开发者来说是巨大的福音，不用面对满屏 [obj release] 和 [pool drain] 这类丑陋不堪的代码了，更重要的是不用整天为对象释放问题搞得寝食难安。但对于许多从 C++ 转到 ObjC 的开发者来说，其实更喜欢 Obj-C++ 混编。Cocoa 负责界面展现，C++ 负责业务逻辑实现，组合起来十分完美。

　　问题是 Obj-C++ 能否完美支持 ARC 呢，特别是把 ObjcC 对象放入 STL 容器的情形下能否正常工作？

　　恭喜大家，答案是肯定的！

测试代码一：

#import 
     
       #import 
      
        using namespace std; class Y {
   public: int value; public:     Y(int val = 0) : value(val)     {
           NSLog(@"Y.Y        (%d)", value);     }     ~Y()     {
           NSLog(@"Y.~Y        (%d)", value);     } }; @interface T : NSObject {
   @private int value;     Y* y; } - (id) initWithValue:(int)v; @end @implementation T - (id) init {
   return [self initWithValue:0]; } - (id) initWithValue:(int)v {
       self = [super init];     self->value = v;     self->y = new Y(v);     NSLog(@"T.init        (%d)", self->value); return self; } - (void)dealloc {
       delete self->y;     NSLog(@"T.dealloc    (%d)", self->value); } @end class X {
   public: int value;     T* t; public:     X(int val = 0) : value(val)     {
           NSLog(@"X.X        (%d)", value);     }     ~X()     {
           NSLog(@"X.~X        (%d)", value);     } };

int main(int argc, char *argv[]) {
       @autoreleasepool     {
           T* t = [[T alloc] initWithValue:1];         {
               vector
     
       vt;             vt.push_back(t);             t = nil;             vt.push_back([[T alloc] initWithValue:2]);             vt.push_back([[T alloc] initWithValue:3]);             {
   //vt.pop_back();                 vt.erase(vt.begin());                 NSLog(@"< first element had been dealloc >");             }             {
                   vt.clear();                 NSLog(@"< all other elements had been dealloc >");             }         }     } }

输出结果：

2012-02-11 19:31:56.256 Switcher[3037:f803] Y.Y        (1) 2012-02-11 19:31:56.258 Switcher[3037:f803] T.init        (1) 2012-02-11 19:31:57.352 Switcher[3037:f803] Y.Y        (2) 2012-02-11 19:31:57.353 Switcher[3037:f803] T.init        (2) 2012-02-11 19:31:57.578 Switcher[3037:f803] Y.Y        (3) 2012-02-11 19:31:57.579 Switcher[3037:f803] T.init        (3) 2012-02-11 19:31:57.786 Switcher[3037:f803] Y.~Y        (1) 2012-02-11 19:31:57.787 Switcher[3037:f803] T.dealloc    (1) 2012-02-11 19:31:58.894 Switcher[3037:f803] < first element had been dealloc > 2012-02-11 19:32:05.227 Switcher[3037:f803] Y.~Y        (2) 2012-02-11 19:32:05.228 Switcher[3037:f803] T.dealloc    (2) 2012-02-11 19:32:05.229 Switcher[3037:f803] Y.~Y        (3) 2012-02-11 19:32:05.230 Switcher[3037:f803] T.dealloc    (3) 2012-02-11 19:32:07.787 Switcher[3037:f803] < other elements had been dealloc >

测试代码二：

int main(int argc, char *argv[]) {
       @autoreleasepool     {
           X* x = new X(1);         x->t = [[T alloc] initWithValue:1];         {
               list
     
       vx;             vx.push_back(x);             vx.push_back(new X(2, [[T alloc] initWithValue:2]));             vx.push_back(new X(3, [[T alloc] initWithValue:3]));             {
                   X* x2 = vx.front();                 vx.pop_front();                 delete x2;                 NSLog(@"< first element had been dealloc >");             }             {
   for(list
      
       ::iterator it = vx.begin(); it != vx.end(); ++it)                     delete (*it);                            NSLog(@"< all other elements had been dealloc >");             }             vx.clear();         }     } }

输出结果：

2012-02-12 02:34:13.403 Switcher[3142:f803] X.X        (1) 2012-02-12 02:34:14.516 Switcher[3142:f803] Y.Y        (1) 2012-02-12 02:34:14.517 Switcher[3142:f803] T.init        (1) 2012-02-12 02:34:26.171 Switcher[3142:f803] Y.Y        (2) 2012-02-12 02:34:26.171 Switcher[3142:f803] T.init        (2) 2012-02-12 02:34:26.174 Switcher[3142:f803] X.X        (2) 2012-02-12 02:34:42.481 Switcher[3142:f803] Y.Y        (3) 2012-02-12 02:34:42.481 Switcher[3142:f803] T.init        (3) 2012-02-12 02:34:42.484 Switcher[3142:f803] X.X        (3) 2012-02-12 02:34:48.856 Switcher[3142:f803] X.~X        (1) 2012-02-12 02:34:48.857 Switcher[3142:f803] Y.~Y        (1) 2012-02-12 02:34:48.858 Switcher[3142:f803] T.dealloc    (1) 2012-02-12 02:35:02.491 Switcher[3142:f803] < first element had been dealloc > 2012-02-12 02:35:07.303 Switcher[3142:f803] X.~X        (2) 2012-02-12 02:35:07.303 Switcher[3142:f803] Y.~Y        (2) 2012-02-12 02:35:07.304 Switcher[3142:f803] T.dealloc    (2) 2012-02-12 02:35:09.319 Switcher[3142:f803] X.~X        (3) 2012-02-12 02:35:09.320 Switcher[3142:f803] Y.~Y        (3) 2012-02-12 02:35:09.321 Switcher[3142:f803] T.dealloc    (3) 2012-02-12 02:35:11.268 Switcher[3142:f803] < all other elements had been dealloc >

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