IOS 诡异！一个停不下来的仪表盘，看在我标题这么长的份上，大神们进来看看吧

Question

RT，遇到一个奇怪的问题，我想要仪表盘在离开主页面的时候停止，回到主页面继续转，我现在做出来的只能一直转，离开页面了他也在转，跟吃了炫迈似的，根本停不下来，不知道是什么原因，麻烦大神们帮忙看看是什么原因

demo我放上网盘了仪表盘demo下载
代码如下

//
//  TableViewController.m
//  仪表盘主页
//
//  Created by liu on 15/5/29.
//  Copyright (c) 2015年 fcar. All rights reserved.
//

#import "TableViewController.h"

#import "GagueCell.h"
static NSString * CELLID = @"cell";

@interface TableViewController ()
@property(nonatomic,assign)BOOL  rota;
@end

@implementation TableViewController

- (void)viewDidLoad
{
    [super viewDidLoad];

 [self.tableView registerClass:[GagueCell class] forCellReuseIdentifier:CELLID];
    self.tableView.bounces = NO;
    self.rota = YES;
    [self.tableView reloadRowsAtIndexPaths:@[[NSIndexPath indexPathForRow:0 inSection:0]] withRowAnimation:UITableViewRowAnimationFade];
    NSLog(@"viewDidLoad");
}

-(void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];
    self.rota =YES;
    [self.tableView reloadRowsAtIndexPaths:@[[NSIndexPath indexPathForRow:0 inSection:0]] withRowAnimation:UITableViewRowAnimationFade];
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

#pragma mark - Table view data source

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
    // Return the number of sections.
    return 1;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    // Return the number of rows in the section.
    return 1;
}



- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    GagueCell*cell = [tableView dequeueReusableCellWithIdentifier:CELLID forIndexPath:indexPath];
    cell.userInteractionEnabled = NO;
    cell.isRefresh = self.rota;
    NSLog(@"cellForRowAtIndexPath");
    return cell;
}


-(CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
return (self.view.bounds.size.height-88-64)/3;
}

-(CGFloat)tableView:(UITableView *)tableView heightForFooterInSection:(NSInteger)section
{
    return 0.1f;
}

-(CGFloat)tableView:(UITableView *)tableView heightForHeaderInSection:(NSInteger)section
{
    return 100.f;
}

-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    NSLog(@"点击了屏幕");
    NSLog(@"didSelectRowAtIndexPath");

}
//这里是storyboard创建的一个导航按钮事件
- (IBAction)nextVC:(UIBarButtonItem *)sender
{
    self.rota = NO;
    [self.tableView reloadRowsAtIndexPaths:@[[NSIndexPath indexPathForRow:0 inSection:0]] withRowAnimation:UITableViewRowAnimationFade];
    [self performSegueWithIdentifier:@"next" sender:nil];
    NSLog(@"nextVC");

}



@end

//接下来是仪表盘的cell
//  GagueCell.m
//  CarBaby
//
//  Created by liu on 15/5/26.
//  Copyright (c) 2015年 fcar. All rights reserved.
//



#import <UIKit/UIKit.h>

@interface GagueCell : UITableViewCell

@property(nonatomic,assign)BOOL isRefresh;
@end






#import "GagueCell.h"
#import <QuartzCore/CADisplayLink.h>
#define WIDTH self.bounds.size.width
#define HEIGH self.bounds.size.height


@interface GagueCell ()

@property (strong, nonatomic)UIImageView *speed;//仪表盘图片
@property (strong, nonatomic)UISlider *speedSlider;//转盘转动的进度条

@property (strong, nonatomic)UIImageView * pin;//指针图片

@property(nonatomic,strong)UIView * view;//放着仪表盘的View

@property(nonatomic,strong)UILabel * speedLabel;
@property(nonatomic,strong)UILabel * consumption;

@property (nonatomic, strong) CADisplayLink *link;
@end

@implementation GagueCell


- (void)setSelected:(BOOL)selected animated:(BOOL)animated {
    [super setSelected:selected animated:animated];

    // Configure the view for the selected state
}

-(void)start
{
    if (self.link) return;
    CADisplayLink *link = [CADisplayLink displayLinkWithTarget:self selector:@selector(update)];

    [link addToRunLoop:[NSRunLoop mainRunLoop] forMode:NSRunLoopCommonModes];
    self.link = link;
    NSLog(@"start");

}

- (void)stopRotating
{

    [self.link invalidate];

    self.link = nil;
    NSLog(@"stopRotating");


}

- (void)update
{

    if (self.speedSlider.value >= 30 )
    {
        self.speedSlider.value ++;
    }
    if(self.speedSlider.value>=330)
    {
        self.speedSlider.value = 0;
    }
    NSLog(@"转盘还在转");
    CGFloat angle = self.speedSlider.value/180*M_PI;

    [UIView animateWithDuration:1 animations:^{
    self.pin.transform = CGAffineTransformMakeRotation(angle);

    }];
    self.consumption.text = [NSString stringWithFormat:@"当前油耗：%.1f L",3.0];
    self.speedLabel.text = [NSString stringWithFormat:@"%@ km/h",@(self.speedSlider.value-30)];
}



-(instancetype)initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(NSString *)reuseIdentifier
{
    if (self = [super initWithStyle:style reuseIdentifier:reuseIdentifier]) {

        self.highlighted = NO;

        self.view = [[UIView alloc] initWithFrame:CGRectZero];
        [self addSubview:self.view];

        self.speed = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 320,10)];

        self.pin = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 320,10)];
        self.pin.image = [UIImage imageNamed:@"pin"];

        self.speed.image = [UIImage imageNamed:@"speed"];

        self.speedSlider = [[UISlider alloc] initWithFrame:CGRectZero];
        [self.speedSlider addTarget:self action:@selector(rotaSliderChange:) forControlEvents:UIControlEventValueChanged];

        self.speedSlider.maximumValue = 330;
        self.speedSlider.minimumValue = 30;
        self.speedSlider.value = 30;
        self.speedSlider.hidden = YES;


        self.backgroundView = nil;
        self.backgroundColor = nil;
        self.selectionStyle = UITableViewCellSelectionStyleNone;


        self.speedLabel = [[UILabel alloc] initWithFrame:CGRectZero];
        self.consumption = [[UILabel alloc] initWithFrame:CGRectZero];
        self.speedLabel.textAlignment = NSTextAlignmentCenter;
        self.consumption.textAlignment = NSTextAlignmentCenter;
        self.speedLabel.textColor = [UIColor whiteColor];
        self.consumption.textColor = [UIColor whiteColor];




        [self.view addSubview:self.speed];
        [self.view addSubview:self.pin];
        [self addSubview:self.speedSlider];
        [self addSubview:self.speedLabel];
        [self addSubview:self.consumption];

        self.view.userInteractionEnabled = NO;
        self.speed.userInteractionEnabled = NO;
        self.pin.userInteractionEnabled = NO;



      }
    return self;
}

- (void)rotaSliderChange:(UISlider *)sender
{



}

-(void)layoutSubviews
{
    [super layoutSubviews];
    CGFloat num =WIDTH>HEIGH?HEIGH:WIDTH;
    //CGPoint center = self.center;
    self.view.frame =CGRectMake((WIDTH-num)/2, 0, num,num);
    self.view.backgroundColor = [UIColor clearColor];
    self.speed.center = CGPointMake(num/2, num/2);
    self.pin.center = CGPointMake(num/2, num/2);
    self.speed.bounds = self.view.bounds;
    self.pin.bounds = self.view.bounds;

    NSLog(@"layoutSubviews");
    self.speedSlider.frame = CGRectMake(0,0, 320, 30);


    self.speedLabel.frame = CGRectMake((WIDTH-num)/2, num-70, num, 25);
    self.consumption.frame = CGRectMake((WIDTH-num)/2, num-25, num, 25);
    self.consumption.text = [NSString stringWithFormat:@"当前油耗：%.1f L",0.f];
    self.speedLabel.text = [NSString stringWithFormat:@"%@ km/h",@(0)];
    self.consumption.text = [NSString stringWithFormat:@"当前油耗：%.1f L",3.0];
    self.speedLabel.text = [NSString stringWithFormat:@"%@ km/h",@(self.speedSlider.value-30)];
}

-(void)setIsRefresh:(BOOL)isRefresh
{
    _isRefresh = isRefresh;
    NSLog(@"setIsRefresh");

    if (self.isRefresh)
    {
        [self start];
    }
    else
    {
        [self stopRotating];

    }

}


@end

界面跳转就是跳转到一个空白页面

Answer 1

- (void)reloadRowsAtIndexPaths:(NSArray *)indexPaths withRowAnimation:(UITableViewRowAnimation)animation NS_AVAILABLE_IOS(3_0);

Reloading a row causes the table view to ask its data source for a new cell for that row.

    NSLog(@"cell before reload = %@", [self.tableView cellForRowAtIndexPath:[NSIndexPath indexPathForRow:0 inSection:0]]);
    [self.tableView reloadRowsAtIndexPaths:@[[NSIndexPath indexPathForRow:0 inSection:0]] withRowAnimation:UITableViewRowAnimationFade];
    NSLog(@"cell after reload = %@", [self.tableView cellForRowAtIndexPath:[NSIndexPath indexPathForRow:0 inSection:0]]);
    [self performSegueWithIdentifier:@"next" sender:nil];

加这2行 你会发现cell已经不是同一个了 你已经失去了对原来cell的控制 原来的displayer也无法控制了, 你NSLog() 会发现displayer 是null
所以正确做法是:

GagueCell*cell = [self.tableView cellForRowAtIndexPath:[NSIndexPath indexPathForRow:0 inSection:0]];
cell.isRefresh = NO;

Answer 2

你在进入下个页面的时候设置有问题。你只是这只了self.rota.对cell.isRefresh完全没有用。
还有你又刷新了cell......
看图吧