ios - Collection View 中的奇怪行为

Question

我有一个包含 25 个单元格的 Collection View 对于一个单元格，我将文本颜色创建为白色。现在，当我重新加载 Collection View 时，其他单元格的文本颜色也会在我重新加载 Collection View 时一个一个地变为白色。我不知道问题出在哪里。这是我的代码。

        if (indexPath.item == 0)
    {
        myCell.hidden=NO;
        NSLog(@"index path = %ld",(long)indexPath.row );
        NSArray *Object=  [[jsonData valueForKey:@"TimeTabledPeriods"]objectAtIndex:0];
        NSLog(@"object %@",Object);
        myCell.roomLabel.text= [NSString stringWithFormat:@"Room: %@", [Object valueForKey:@"RoomDescription"]];
        myCell.subjectLabel.text =  [Object valueForKey:@"SubjectDescription"];
        [myCell.redXbuttonOutlet setTag:indexPath.row];
        [myCell.redXbuttonOutlet addTarget:self action:@selector(buttonPressed:) forControlEvents:UIControlEventTouchUpInside];
        myCell.noSessionView.backgroundColor=[UIColor clearColor];
        myCell.myLearningChoicesBackground.hidden=YES;

        if ([[Object valueForKey:@"Changed"] isEqualToString:@"YES"])
        {
            if ([[Object valueForKey:@"ChangedColorCode"] isEqualToString:@"Present"])
            {
                myCell.noSessionView.backgroundColor=[UIColor colorWithRed:97.0/255.0 green:182.0/255.0 blue:73/255.0 alpha:1];

    //The below lines to change the text color to white is written only for index path  0
                myCell.roomLabel.textColor=[UIColor whiteColor];
                myCell.subjectLabel.textColor=[UIColor whiteColor];

            }

        }
//code for other cells

    if (indexPath.item == 1)
{
    myCell.hidden=NO;
    NSLog(@"index path = %ld",(long)indexPath.row );
    NSArray *Object=  [[jsonData valueForKey:@"TimeTabledPeriods"]objectAtIndex:0];
    NSLog(@"object %@",Object);
    myCell.roomLabel.text= [NSString stringWithFormat:@"Room: %@", [Object valueForKey:@"RoomDescription"]];
    myCell.subjectLabel.text =  [Object valueForKey:@"SubjectDescription"];
    [myCell.redXbuttonOutlet setTag:indexPath.row];
    [myCell.redXbuttonOutlet addTarget:self action:@selector(buttonPressed:) forControlEvents:UIControlEventTouchUpInside];
    myCell.noSessionView.backgroundColor=[UIColor clearColor];
    myCell.myLearningChoicesBackground.hidden=YES;

    if ([[Object valueForKey:@"Changed"] isEqualToString:@"YES"])
    {
        if ([[Object valueForKey:@"ChangedColorCode"] isEqualToString:@"Present"])
        {
            myCell.noSessionView.backgroundColor=[UIColor colorWithRed:97.0/255.0 green:182.0/255.0 blue:73/255.0 alpha:1];

        }

    }

    if (indexPath.item == 3)
{
    myCell.hidden=NO;
    NSLog(@"index path = %ld",(long)indexPath.row );
    NSArray *Object=  [[jsonData valueForKey:@"TimeTabledPeriods"]objectAtIndex:0];
    NSLog(@"object %@",Object);
    myCell.roomLabel.text= [NSString stringWithFormat:@"Room: %@", [Object valueForKey:@"RoomDescription"]];
    myCell.subjectLabel.text =  [Object valueForKey:@"SubjectDescription"];
    [myCell.redXbuttonOutlet setTag:indexPath.row];
    [myCell.redXbuttonOutlet addTarget:self action:@selector(buttonPressed:) forControlEvents:UIControlEventTouchUpInside];
    myCell.noSessionView.backgroundColor=[UIColor clearColor];
    myCell.myLearningChoicesBackground.hidden=YES;

    if ([[Object valueForKey:@"Changed"] isEqualToString:@"YES"])
    {
        if ([[Object valueForKey:@"ChangedColorCode"] isEqualToString:@"Present"])
        {
            myCell.noSessionView.backgroundColor=[UIColor colorWithRed:97.0/255.0 green:182.0/255.0 blue:73/255.0 alpha:1];

        }

    }

//等等

Answer 1

这种行为没有什么“奇怪”的，这是没有正确处理单元重用的结果。您在第一个 if 子句中将文本设置为白色，但绝不会在其他 if 子句中将其设置回任何其他颜色。因此，当该单元格被重复使用时，它的文本仍将设置为白色。看起来每个 if 子句中的代码，除了颜色变化之外都是相同的，所以你甚至不应该为每个项目都拥有所有这些 if 子句；您需要重构代码以消除所有重复。在任何 if 子句之外，如果您实际上仍然需要它们中的任何一个，则应仅将第 0 项的文本颜色设置为白色，将所有其他项设置为黑色，

myCell.roomLabel.textColor = (indexPath.item == 0)? [UIColor whiteColor] : [UIColor blackColor];
myCell.subjectLabel.textColor= (indexPath.item == 0)? [UIColor whiteColor] : [UIColor blackColor];