当我展示另一个视图控制器时，NSTimer 不会停止

Question

我有一个 viewController1 设置定时器。
当计时器倒计时到 0 时，我会呈现 viewController2。
定时器也一直在运行，虽然我调用了定时器函数invalidate
然后我标记了当前的视图控制器代码，它似乎正确停止了。

//ViewController2 *vc = [[ViewController2 alloc] init];
//[self presentViewController:vc animated:false completion:nil];

代码有什么问题？

#import "ViewController.h"
#import <WebKit/WebKit.h>
#import "ViewController2.h"

@interface ViewController ()<WKScriptMessageHandler, WKNavigationDelegate,WKUIDelegate>

    @property (nonatomic,strong) WKWebView* webView;
    @property (nonatomic, strong) WKWebViewConfiguration * webConfig;
    @property (nonatomic, strong) NSTimer *timer;
    @property (nonatomic) int count;

    @end

    @implementation ViewController

    - (void)viewDidLoad {
        [super viewDidLoad];

        self.webView = [[WKWebView alloc] initWithFrame:self.view.frame configuration:[self createWKWebApp]];
        [self.view addSubview: self.webView];
        [self.webView.configuration.preferences setValue:@YES forKey:@"allowFileAccessFromFileURLs"];
        self.webView.scrollView.bounces = NO;
        [self.webView setContentMode:UIViewContentModeScaleAspectFit];
        self.webView.navigationDelegate = self;
        self.webView.UIDelegate = self;

        NSURL *url = [NSURL URLWithString:@"https://www.google.com.tw"];
        NSURLRequest *request = [NSURLRequest requestWithURL:url];
        [self.webView loadRequest:request];

        self.count = 5;

        self.timer = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(timerFired) userInfo:nil repeats:YES];
    }

    -(void)timerFired {

        NSLog(@"===) self.count : %d", self.count);

            if (self.count == 0) {

                ViewController2 *vc = [[ViewController2 alloc] init];
                [self presentViewController:vc animated:false completion:^{
                    [self.timer invalidate];
                    self.timer = nil;
                }];

            } else {
                self.count -= 1;
            }

    }


    - (WKWebViewConfiguration *)createWKWebApp {
        WKWebViewConfiguration *config = [[WKWebViewConfiguration alloc] init];
        WKUserContentController *userContent = [[WKUserContentController alloc] init];

        config.userContentController = userContent;

        return config;
    }

    - (void)userContentController:(WKUserContentController*)userContentController didReceiveScriptMessage:(WKScriptMessage*)message {


    }

    @end

Answer 1

在呈现 ViewController 之前，停止计时器

[self.timer invalidate];
 self.timer = nil;
ViewController2 *vc = [[ViewController2 alloc] init];
[self presentViewController:vc animated:false completion:nil];

Answer 2

在 viewWillDisappear 委托方法中使计时器无效，并在视图再次出现时再次触发。