iOS：XCode 4.2开始Objective-C支持ARC-技术开发专区

iOS：XCode 4.2开始Objective-C支持ARC

作者：~怪^_*兽~ 编辑：景保玉 2012-02-13 10:06 来源：博客园

　　【IT168技术】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 <vector>
#import <list>
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<T*> 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<X*> 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<X*>::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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