防止 UIcollectionView 中的单元格堆叠

Question

我一直在 Objective C 中使用苹果地图开发一款收集游戏。您收集的每个项目都显示在 uicollectionview 中。它工作得很好，直到你达到 15 左右并且必须开始向下滚动视图，然后我得到了图片中看到的奇怪的堆叠效果。 kanohi 发现变量工作正常，其中有 21 个单元格用于 21 个项目。 这是我的代码（或者至少是重要的部分）：

//
//  wallOfMasksController.m
//  Matoran Quest
//
//  Created by Job Dyer on 12/11/23.
//

#import "wallOfMasksController.h"
#import "UICollectionViewCell+CollectionViewCell.h"

@interface wallOfMasksController ()<UICollectionViewDelegate, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout>

@end

@implementation wallOfMasksController

NSArray *maskArray; //our mask array
NSArray *selectedMaskArray; //the mask we want to know more about
UIImage *maskImage2; //the colourized mask image
UIImage *outPutMask; //the mask we take to the individual mask viewer
NSMutableArray *imagesInCollection; //an array of all the images
NSMutableArray *collectedMasks2; //a list of the kinds of masks the player has collected. 1 entry for each unique kind of mask (colour as well as type)

- (void)viewDidLoad {
    [super viewDidLoad];
    maskArray = [[NSUserDefaults standardUserDefaults] objectForKey:@"PlayerMasks"]; //get the players masks from the user defaults and make an array of them
    //NSLog(@"monkey: %@", [[NSUserDefaults standardUserDefaults] objectForKey:@"PlayerMasks"]);
    _maskGrid.delegate = self;
    _maskGrid.dataSource = self;
    //NSLog(@"%@", maskArray);
    [_maskCount setText:[NSString stringWithFormat:@"Kanohi found: %d", (int)maskArray.count]]; // how many masks do we have?
    imagesInCollection = [[NSMutableArray alloc] init];
    
    collectedMasks2 = [[NSUserDefaults standardUserDefaults] objectForKey:@"PlayerMaskCollectionList"];
    if(collectedMasks2 == NULL){ //if there is no player masks collection key yet
        collectedMasks2 = [[NSMutableArray alloc] init];
        //NSLog(@"refreshing2");
        [[NSUserDefaults standardUserDefaults] setObject:collectedMasks2 forKey:@"PlayerMaskCollectionList"]; //set it if it doesnt exist
        
    }
    [_collectionCount setText:[NSString stringWithFormat: @"Collection: %d/183", (int)collectedMasks2.count]];
}


- (nonnull __kindof UICollectionViewCell *)collectionView:(nonnull UICollectionView *)collectionView cellForItemAtIndexPath:(nonnull NSIndexPath *)indexPath {
    //NSLog(@"Got this far");
    CollectionViewCell *cell3 = [_maskGrid dequeueReusableCellWithReuseIdentifier:@"cell3" forIndexPath:indexPath];
    //[cell1.customLabel setText:itemArray[indexPath.row]];
    //make a label
    //UILabel *itemName = [[UILabel alloc]initWithFrame:CGRectMake(91, 15, 0, 0)];
    //
    
    NSArray *maskInterior = [maskArray objectAtIndex:indexPath.row]; //get the mask list to get out the name of the mask
    //NSLog(@"%@", maskInterior)
    NSString *maskNameAndColour = maskInterior[0];
    NSArray *maskColourAndName; //array of seperated name and colour
    NSString *maskName;
    int noColourFlag = 0; //check if mask is special and skip colourizing
    if([maskNameAndColour isEqualToString: @"vahi"]){ //seperate things out if needed
        maskName = @"vahi";
        noColourFlag = 1;
    }
    else if([maskNameAndColour isEqualToString: @"avohkii"]){
        maskName = @"avohkii";
        noColourFlag = 1;
    }
    else if([maskNameAndColour isEqualToString: @"infected hau"]){
        maskName = @"infected hau";
        noColourFlag = 1;
    }

    else{
        maskColourAndName = [maskNameAndColour componentsSeparatedByString:@" "];
        maskName = maskColourAndName[1];
    }
    /*
    //check and replace problem names (legacy). this will cause the app to crash if the string does not have a hyphen added
    if([maskNameAndColour containsString:@"light green"]){
        [maskInterior replaceObjectAtIndex:0 withObject:@"light green"];
        [maskArray replaceObjectAtIndex:indexPath.row withObject:maskInterior];
    }
    */
    
    UIImageView *maskImage=[[UIImageView alloc]initWithFrame:CGRectMake(18, 18, 64, 64)];
    if(noColourFlag == 0){ //if its not a special flag, then colourize it
        UIColor *tempColor = [self colourCaser: maskColourAndName[0]]; //colour the image
        maskImage2 = [UIImage imageNamed:[NSString stringWithFormat: @"%@", maskName]];
        //[maskImage2 imageWithTintColor:tempColor];
        maskImage2 = [self colorizeImage:maskImage2 color:tempColor];
        [maskImage setImage:maskImage2]; //set an image with a colour
        [maskImage2 setAccessibilityIdentifier: maskNameAndColour];
        if(maskImage2 != nil){
            [imagesInCollection addObject: maskImage2];
        }
        else{
            NSLog(@"adding to collection error");
        }
        //NSLog(@"%@", imagesInCollection);
    }
    else{
        [maskImage setImage:[UIImage imageNamed:[NSString stringWithFormat: @"%@", maskName]]]; //get the image named the name of the mask without the colour
    }

    [cell3 addSubview:maskImage];//Add it to the view of your choice.
    
    UILabel *maskNameLabel =[[UILabel alloc]initWithFrame:CGRectMake(25, 70, 50, 50)];//Set frame of label in your view
    //[itemName setBackgroundColor:[UIColor lightGrayColor]];//Set background color of label.

    @try {
        [maskNameLabel setText: [NSString stringWithFormat: @"%@",maskNameAndColour]];
    }
    @catch (NSException *exception) {
        [maskNameLabel setText: @""];
    }
    @finally {
      //Display Alternative
    }
    //NSLog(@"here: %@", maskArray);
    
    //[maskName setText: @"mask"];
    [maskNameLabel setAdjustsFontSizeToFitWidth:true];
    [maskNameLabel setFont:[UIFont fontWithName:@"Goudy Trajan Regular" size:10]];
    [maskNameLabel setTextColor:[UIColor whiteColor]];//Set text color in label.
    [maskNameLabel setTextAlignment:NSTextAlignmentCenter];//Set text alignment in label.
    [maskNameLabel setBaselineAdjustment:UIBaselineAdjustmentAlignBaselines];//Set line adjustment.
    [maskNameLabel setLineBreakMode:NSLineBreakByCharWrapping];//Set linebreaking mode..
    [maskNameLabel setNumberOfLines:1];//Set number of lines in label.
    //[itemName.layer setCornerRadius:40.0];//Set corner radius of label to change the shape.
    //[itemName.layer setBorderWidth:1.0f];//Set border width of label.
    [maskNameLabel setClipsToBounds:YES];//Set its to YES for Corner radius to work.
    [maskNameLabel.layer setBorderColor:[UIColor blackColor].CGColor];//Set Border color.
    [cell3 addSubview:maskNameLabel];//Add it to the view of your choice.
     
    
    
    return cell3;
    
}



- (NSInteger)collectionView:(nonnull UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
    return maskArray.count;
    
}

- (CGSize)collectionView:(UICollectionView *)collectionView layout:   (UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath{
    return CGSizeMake(100, 100);
}

- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath{ //tap brings up delete dialog
    //NSLog(@"Tapped %d", (int)indexPath.row);
    selectedMaskArray = maskArray[indexPath.row]; //assign the new mask to a temporary holding cell
    for (int i = 0; i <= (imagesInCollection.count -1); i++)
    {
        UIImage *tempImage = imagesInCollection[i]; //some technical wizardry to get the correct mask and colour displaying in the individual mask display screen
        //NSLog(@"A: %@", maskName);
        //NSLog(@"B: %@", tempImage.accessibilityIdentifier);
        if([tempImage.accessibilityIdentifier isEqualToString: selectedMaskArray[0]] ){
            outPutMask = tempImage;
        }
    }
    
    [self performSegueWithIdentifier:@"selectedMask" sender:self];
}

有人知道如何阻止这种情况发生吗？ （Objective C 请回答，Swift 有时候转换成 Obj-C 有点痛苦）

Answer 1

当重复使用单元格时，您会一次又一次地重新添加

maskImage

和

maskNameLabel

。尝试将其作为集合单元格的子视图，然后重新分配框架、颜色、图像、文本等，即：

- (nonnull __kindof UICollectionViewCell *)collectionView:(nonnull UICollectionView *)collectionView cellForItemAtIndexPath:(nonnull NSIndexPath *)indexPath {
    CollectionViewCell *cell3 = [_maskGrid dequeueReusableCellWithReuseIdentifier:@"cell3" forIndexPath:indexPath];
    if (noColourFlag == 0) {
        ...
        [cell.maskImage setImage:maskImage2];
    } else {
        [cell.maskImage setImage:[UIImage imageNamed:[NSString stringWithFormat: @"%@", maskName]]];
    }
    //The same with maskNameLabel
}