UIVIew中的UITableView在滚动时重新加载时冻结

Question

I have a UIViewController that has a UITableView in it. I wanted to have a Search bar which displays text and has Button that pulls up a UIPickerView with options. when I select any option from the UIPickerView the tableView reloads. There are two problems that I have noticed so far:

1. Each cell of my tableView covers approx. 400px in height; when I scroll the tableView and leave it in a position where the cell is halfway/little more than halfway out, and I reload the table with 0 rows the entire app freezes, and the XCode does not record any error

2. When I pull up the Picker and make a selection while making the tableview in the background scroll, the app freezes again, which not recording any error

In either case, the app does not crash(does not quit), but freezes the UI making any other interaction impossible. Any kind of help would be appreciated. Thanks

Following is the code: - Code for custom Search bar `

- (void)drawRect:(CGRect)rect
{
    // Drawing code
    _leftMonthButton=[[UIButton alloc] initWithFrame:CGRectMake(leftArrowX, 0, leftArrowWidth, 40)];
    _leftMonthButton.imageView.contentMode=UIViewContentModeScaleAspectFit;
    [_leftMonthButton setImage:[UIImage imageNamed:@"arrow-left.png"] forState:UIControlStateNormal];
    [_leftMonthButton addTarget:self action:@selector(monthSwitched:) forControlEvents:UIControlEventTouchUpInside];


    _rightMonthButton=[[UIButton alloc] initWithFrame:CGRectMake(rightArrowX, 0, rightArrowWidth, 40)];
    _rightMonthButton.imageView.contentMode=UIViewContentModeScaleAspectFit;
    [_rightMonthButton setImage:[UIImage imageNamed:@"arrow-right.png"] forState:UIControlStateNormal];
    [_rightMonthButton addTarget:self action:@selector(monthSwitched:) forControlEvents:UIControlEventTouchUpInside];

    _dropDownButton=[UIButton buttonWithType:UIButtonTypeCustom];
    _dropDownButton.frame=CGRectMake(downArrowX, 0, downArrowWidth, 40);
    _dropDownButton.imageView.contentMode=UIViewContentModeScaleAspectFit;
    [_dropDownButton setImage:[UIImage imageNamed:@"downArrow.png"] forState:UIControlStateNormal];
    [_dropDownButton addTarget:self action:@selector(dropDownButtonClicked:) forControlEvents:UIControlEventTouchUpInside];

    _activeMonthIndex=1;

    [self addSubview:_leftMonthButton];
    [self addSubview:_rightMonthButton];
    [self addSubview:_dropDownButton];

    CGRect frame=_dropDownButton.frame;
    frame=CGRectMake(downArrowX, 0, downArrowWidth, 40);
    _dropDownButton.frame=frame;
}


(void)dropDownButtonClicked:(UIButton*)sender
{

    [self.searchBarDelegate brandPickerClicked];
}

(void)monthSwitched:(UIButton*)sender
{
    if (sender==_leftMonthButton)
    {
        if (_activeMonthIndex>0)
        {
            if (_rightMonthButton.alpha==0) _rightMonthButton.alpha=1;
            _activeMonthIndex-=1;
            _monthLabel.text=_activeMonths[_activeMonthIndex];
        }
        if (_activeMonthIndex==0)
        {
            _leftMonthButton.alpha=0;
        }
    }
    else
    {
        if (_activeMonthIndex<2)
        {
            if (_leftMonthButton.alpha==0) _leftMonthButton.alpha=1;
            _activeMonthIndex+=1;
            _monthLabel.text=_activeMonths[_activeMonthIndex];
        }
        if (_activeMonthIndex==2)
        {
            _rightMonthButton.alpha=0;
        }
    }
    [self.searchBarDelegate monthChangedTo:_monthLabel.text];
}`

-Code for tableView implementing the searchBar

` - (void)viewDidLoad { [super viewDidLoad]; // Do any additional setup after loading the view.

    _searchBar=[[CalendarSearchBar alloc] initWithFrame:CGRectMake(0, 0, [UIScreen mainScreen].bounds.size.width, 40)];
    _searchBar.searchBarDelegate=self;
    [_headerView addSubview:_searchBar];

    self.calendarTable.dataSource=self;
    self.calendarTable.delegate=self;
    self.calendarTable.allowsSelection=false;

    UIView *tableViewFooter=[[UIView alloc] initWithFrame:CGRectMake(0, 0, [UIScreen mainScreen].bounds.size.width, 23)];
    tableViewFooter.backgroundColor=[UIColor colorwithHexString:@"333333" alpha:1];

    [self.calendarTable setTableFooterView:tableViewFooter];

    _calendar=[CalendarData sharedReleaseData];
    _currentTableRowItems=_calendar;

    CGFloat screenHeight=[UIScreen mainScreen].bounds.size.height;
    CGFloat screenWidth=[UIScreen mainScreen].bounds.size.width;

    _picker=[[UIPickerView alloc] initWithFrame:CGRectMake(0, screenHeight-400, screenWidth, 400.0)];
    _picker.backgroundColor=[UIColor colorwithHexString:@"666666" alpha:1];
    _picker.dataSource=self;
    _picker.delegate=self;
}

    - (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
    {
        return 1;
    }

    - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
    {
        return _currentTableRowItems.count;
    }


- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    calendarCell *cell = (CalendarCell*)[tableView dequeueReusableCellWithIdentifier:@"calendarCell" forIndexPath:indexPath];

    CalendarObject *object=_currentTableRowItems[indexPath.row];

    cell.backgroundColor=[UIColor colorwithHexString:@"333333" alpha:1];
    cell.calendarCardView.backgroundColor=[UIColor whiteColor];
    return cell;
}


- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
    return [UIScreen mainScreen].bounds.size.height*479/568;
}

// Picker Controller Delegate Methods
-(void)pickerClicked
{
    if (![_picker isDescendantOfView:self.view])
    {
        [self.calendarTable setContentOffset:CGPointZero animated:YES];
        [self.calendarTable setScrollEnabled:NO];
        [self.view addSubview:_picker];
    }
}

-(void)updateTableViewObjectsWithSearchString:(NSString*)searchString andSearchContext:(SearchContext)searchContext
{
    [_currentTableRowItems removeAllObjects];

    if (searchContext==date)
    {
            for (CalendarObject *object in _calendar.calendarArray)
            {
                if ([object.date.text compare:searchString options:NSCaseInsensitiveSearch]==NSOrderedSame && [object.monthName compare:_searchBar.monthLabel.text options:NSCaseInsensitiveSearch]==NSOrderedSame) [_currentTableRowItems addObject:object];
            }
        }
    }

    dispatch_async(dispatch_get_main_queue(), ^(void){
        [self.releaseCalendarTable reloadData];
    });

   // [self.calendarTable setContentOffset:CGPointZero animated:YES];
}

//Data Source Picker View
-(NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView
{
    return 1;
}

-(NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component
{
    return _searchBar.dates.count;
}

- (NSAttributedString *)pickerView:(UIPickerView *)pickerView attributedTitleForRow:(NSInteger)row forComponent:(NSInteger)component
{
    NSString *title = _searchBar.dateArray[row];
    NSAttributedString *attString = [[NSAttributedString alloc] initWithString:title attributes:@{
                                                                                                  NSForegroundColorAttributeName: [UIColor whiteColor],
                                                                                                  NSFontAttributeName: [UIFont fontWithName:@"UnitedSansRegTT-Bold" size:18.0f],
                                                                                                  }];
    return attString;
}

//PickerView Delegate
-(void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row
      inComponent:(NSInteger)component
{
    [self.calendarTable setScrollEnabled:YES];
    _searchBar.label.text=_searchBar.brandNames[row];
    [self updateTableViewObjectsWithSearchString:_searchBar.label.text andSearchContext:date];
    [self.picker removeFromSuperview];
}

`

Answer 1

我想我遇到了问题，您正在drawrect上添加子视图。不要那样做的rect rect仅用于绘制特定的视图。这是一个非常糟糕的做法，将其移动到initwithframe中，或者如果连接了笔尖，则在awakefromnib中将其移动并不要不要添加和删除pickerview，在其中创建一个视图将是pickerview并隐藏/显示它