自定义UITableViewCell prepareForReuse未按预期工作

Question

我的prepareForReuse不能正常工作。我有一个UITableView，它应该只在表的第一部分的第一行中有一个login UIButton。但是，在prepareForReuse中，当我删除login按钮时，它会停留在下一批行中。(演示-> http://pixori.al/8g3v的视频)

这是我的自定义UITableViewCell

#import "MAGradeCell.h"

@implementation MAGradeCell

- (id)initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(NSString *)reuseIdentifier cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    self = [super initWithStyle:style reuseIdentifier:reuseIdentifier];
    if (self) {
        // Initialization code
    }
    return self; }

-(void)layoutSubviews{
    [super layoutSubviews]; }

- (void)prepareForReuse {
    self.loginButton = nil;
    [self removeFromSuperview];
    [self.loginButton removeFromSuperview];
    self.textLabel.text = nil;

    [super prepareForReuse]; }

/*
 - (void)setSelected:(BOOL)selected animated:(BOOL)animated  {  [super setSelected:selected animated:animated];    // Configure the view for the selected state  }*/

@end

和我的视图控制器中设置单元格的部分(cellForRowAtIndexPath)。即我把QBFlatButton和所有东西放在哪里：

- (MAGradeCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    static NSString *CellIdentifier = @"CellIdentifier";
    //UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    MAGradeCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];


//    // Redefine layout variables in method from `viewDidLoad`
    CGFloat inset = 20; // For padding


    if (! cell) {
        cell = [[MAGradeCell alloc] initWithStyle:UITableViewCellStyleValue1 reuseIdentifier:CellIdentifier cellForRowAtIndexPath:indexPath];
    }


    // Sets up attributes of each cell
    cell.selectionStyle = UITableViewCellSelectionStyleNone;
    cell.backgroundColor = [UIColor colorWithWhite:0 alpha:0.2];
    cell.textLabel.textColor = [UIColor whiteColor];
    cell.detailTextLabel.textColor = [UIColor whiteColor];
    QBFlatButton* loginButton = nil;

    if (indexPath.section == 0) {
        if (indexPath.row == 0) {
            [self configureHeaderCell:cell title:@"Grades"];

                UIView *cellView = cell.contentView;
                loginButton = [[QBFlatButton alloc] initWithFrame:CGRectMake((cellView.frame.size.width - (80 + inset)), 18, 80, (cellView.frame.size.height -(cellView.frame.size.height/2)))];
                [loginButton addTarget:self action:@selector(loginButtonWasPressed)forControlEvents:UIControlEventTouchUpInside];
                loginButton.faceColor = [UIColor grayColor];
                loginButton.sideColor = [UIColor clearColor];

                loginButton.radius = 6.0;
                loginButton.margin = 4.0;
                loginButton.depth = 3.0;
                loginButton.alpha = 0.3;

                loginButton.titleLabel.font = [UIFont fontWithName:@"HelveticaNeue-Light" size:20];
                [loginButton setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
                [loginButton setTitle:@"Login" forState:UIControlStateNormal];
                [cellView addSubview:loginButton];
        } else {
            cell.selectionStyle = UITableViewCellSelectionStyleBlue;
            MAGradeClient *grade = [[MAGradeClient alloc] init];
            [self configureGradesCell:cell grade:grade];
        }
    } else if (indexPath.section == 1) {
        if (indexPath.row == 0) {
            [self configureHeaderCell:cell title:@"Hourly Forecast"];
        }
        else {
            // Get hourly weather and configure using method
            MACondition *weather = [MAManager sharedManager].hourlyForecast[indexPath.row - 1];
            [self configureHourlyCell:cell weather:weather];
        }
    }
    else if (indexPath.section == 2) {
        if (indexPath.row == 0) {
            [self configureHeaderCell:cell title:@"Daily Forecast"];
        }
        else if (indexPath.section == 2) {
            // Get daily weather and configure using method
            MACondition *weather = [MAManager sharedManager].dailyForecast[indexPath.row - 1];
            [self configureDailyCell:cell weather:weather];
        }
    }

    return cell;
}

Answer 1

如果您这样做了：

self.loginButton = nil;

然后试着这样做：

[self.loginButton removeFromSuperview];

它不会起作用，因为你已经删除了引用。

考虑对此单元格使用不同的单元格标识符，因为如果要添加和删除按钮，这并不是真正的重用。也可以考虑隐藏/显示按钮。如果您想要删除它，则将代码更改为：

- (void)prepareForReuse
{
    [self.loginButton removeFromSuperview];
    self.loginButton = nil;

    self.textLabel.text = nil;

    [super prepareForReuse];
}

看起来你也从来没有设置过：

cell.loginButton = loginButton;

因此，该单元格可能无论如何都没有引用可用…