Xcdoe 4 下的内存泄露检测

        xcode在发布初就提供Insruments供我们内存调试，在这里我简单介绍下Instruments在xcode4下的使用，该文以xcode4.3.1作为范本。

编写一个单页面工程，命名为Memleak，为了便于测试内存泄露，这里选取两个函数，一个是对传统的C 中char* 字符数组的内存泄露，另一个是对object-C下 NSMutableArray 类的泄露。先贴上代码：

MemLeakViewController.h

#import <UIKit/UIKit.h>

@interface MemLeakViewController : UIViewController

@end

 

MemLeakViewController.m

#import "MemLeakViewController.h"

@interface MemLeakViewController ()

- (void) leakCstring;
- (void) leakArray;

@end

@implementation MemLeakViewController

- (void) leakCstring
{
    UIAlertView* alert = [[UIAlertView alloc]initWithTitle:@"String mem leak testing" message:@"You try to leak string memory" delegate:nil cancelButtonTitle:@"ok" otherButtonTitles:nil];
    [alert show];
    char* leakstring = malloc(sizeof(char)*128);
    leakstring = NULL;
    [alert release];

}

- (void) leakArray
{
    UIAlertView* alert = [[UIAlertView alloc]initWithTitle:@"Array mem leak testing" message:@"You try to leak Arr memory" delegate:nil cancelButtonTitle:@"ok" otherButtonTitles:nil];
    [alert show];
    NSArray *leakarray = [ [NSMutableArray alloc] init ];
    leakarray = nil;
    [alert release];
}

- (void)viewDidLoad
{

    /*  显示标题 */
    [super viewDidLoad];
    UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 320, 160)];
    label.textAlignment = UITextAlignmentCenter;
    label.text = @"This is mem leak testing!";
    [self.view addSubview:label];
    [label release];
   
    /*  泄露字符串按钮 */  

   UIButton *button1 = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    [button1 setTitle:@"Leak Cstring" forState:UIControlStateNormal];
    [button1 setFrame:CGRectMake(20, 160, 120, 30)];
    [button1 addTarget:self action:@selector(leakCstring) forControlEvents:UIControlEventTouchUpInside];

    [self.view addSubview:button1];

    /* 泄露NSMutableArray按钮 */
    UIButton *button2 = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    [button2 setTitle:@"Leak Array" forState:UIControlStateNormal];
    [button2 setFrame:CGRectMake(20, 300, 120, 30)];
    [self.view addSubview:button2];
    [button2 addTarget:self action:@selector(leakArray) forControlEvents:UIControlEventTouchUpInside];

}

        编译通过后在顶端的Xcode标签下选择Open Developer Tool 从菜单里选择Instruments，Instruments 工具集里包含了各种牛逼闪闪的调试工具。 

 

 选取内存泄露检测工具Leaks，可以看看到如下界面：

        点击左上角的“Choose Target”选取调试的目标文件。一般xcode 生成的目标文件存储在/users/用户名/library/Developer/Xcode/DeriveData中，注意在添加目标文件前先编译一次，生成目标文件。运行Record按钮，如下图所示：

        正常运行程序，同时会出现以时间为坐标的内存监测进度。分别点击“Leak Cstring”和“Leak Array”。在一定时延下会在Leaks 坐标中出现黄色竖条，其高度是泄露内存的大小。在下侧的 Leaked Object可以参看具体的信息，包括泄露内存大小和地址。