内存泄漏

最新推荐文章于 2025-03-18 08:45:15 发布

toro宇

最新推荐文章于 2025-03-18 08:45:15 发布

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分类专栏： iOS深度开发

本文链接：https://blog.youkuaiyun.com/he317165264/article/details/51453522

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本文探讨了iOS应用中定时器未正确释放导致的dealloc方法未被调用的问题。通过具体示例说明如何在viewWillDisappear或back按钮事件中取消定时器，确保内存正常释放。

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1。代理 weak解决循环引用

2 ，block 实例变量

3，注册观察着，要在delloc 中注销观察着

4，timer

刚调试程序时发现一个很诡异的问题，我从ViewController A push进 ViewController B，在从B back时发现程序不会执行B里面的delloc（），很诡异的问题，因为按理说此时点击back是执行pop操作的，是会执行delloc()函数的，但经调试发现确实没有执行。

后来经过google发现，

The dealloc method was not being called if any of the references held by a viewcontroller were still in memory.

也就是说，我当前View B 内存中计数器不为0，经排查发现，我是在ViewDidLoad函数里面开启了一个time类型，

timer=[NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(updateTime:) userInfo:nil repeats:YES];

这一句调用的时候对 target:self 进行了retain,这时候你pop回上一级，self的引用计数还剩1，所以铁定不会dealloc，我的解决办法是在- (void)viewWillDisappear:(BOOL)animated（）

将定时器注销掉，对象的引用计数为0 方可走 delloc

NSTimer

@interface ForgetPasswordViewController ()
{
NSTimer *timer;
int count;
}

count = 60;
timer = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(updateBtnState) userInfo:nil repeats:YES];

-(void)updateBtnState
{
    if (count == 0) {
        if (timer) {
            [timer invalidate];
            timer = nil;
        }
        self.timeLabel.text = @"获取验证码";
        self.getCodeBtn.enabled = YES;
        self.codeStr = nil;
    }else
    {
        dispatch_async(dispatch_get_main_queue(), ^{
            //更新UI操作
            self.timeLabel.text = [NSString stringWithFormat:@"%d%@",count,@"秒"];
//            [self.getCodeBtn setTitle:@"" forState:UIControlStateNormal];
            self.getCodeBtn.enabled = NO;
            count--;
        });
    }

}

- (IBAction)backBtn:(id)sender {
    [self.navigationController popViewControllerAnimated:YES];
    if (timer) {
        [timer invalidate];
    }
}

-delloc{} 才会走

GCD

@implementation RegisterViewController
{
dispatch_source_t _timer;
dispatch_source_t _distimer;
}

__block int timeout = 60;
    dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
    _timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, queue);
    dispatch_source_set_timer(_timer, dispatch_walltime(NULL, 0), 1.0*NSEC_PER_SEC, 0);
    dispatch_source_set_event_handler(_timer, ^{

        if (timeout <= 0) {
            dispatch_source_cancel(_timer);

            dispatch_async(dispatch_get_main_queue(), ^{

                self.mGetCodeBtn.hidden = NO;
                self.mTimeLabel.text = @"Get code";
                [self.mGetCodeBtn setTitle:@"Get code" forState:UIControlStateNormal];
                [self.mGetCodeBtn setBackgroundColor:[UIColor colorWithHex:@"#D62961"]];
                [self.mGetCodeBtn setTitleColor:[UIColor whiteColor] forState:UIControlStateNormal];
            });
        }else
        {
            NSString *strtime = [NSString stringWithFormat:@"%.2d",timeout];
            dispatch_async(dispatch_get_main_queue(), ^{

                self.mGetCodeBtn.hidden = YES;
                self.mTimeLabel.text = [NSString stringWithFormat:@"%@s重新发送",strtime];
            });
            timeout -- ;
        }
    });
    dispatch_resume(_timer);
}