奇怪的位置uicollectionview标题部分xcode

Question

我不知道为什么，但对于UICollectionView的偶数部分，标题错位。
然而，对于奇数编号的部分是正确的。

这是我的代码：

#import "ExosViewController.h"
#import "ExCell.h"
#import "ExerciseDatabase.h"
#import "Exercise.h"
#import "HeaderView.h"

@implementation ExosViewController
@synthesize backgroundImage;
@synthesize titles;
@synthesize subtitles;
@synthesize enonces;
@synthesize numbers;
@synthesize parts;

NSInteger nbItemsInPart[7];
int item =0;
int nbSections = -1;

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];

    [self setBackground];
    [self setBarPreferences];
    [self loadData];
    [self addCollView];
}

- (void)setBackground
{
    self.backgroundImage = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"fond.png"]];
    self.backgroundImage.frame = self.view.bounds;
    self.backgroundImage.autoresizingMask=UIViewAutoresizingFlexibleWidth|UIViewAutoresizingFlexibleHeight;
    self.backgroundImage.contentMode = UIViewContentModeScaleAspectFill;

    [self.view addSubview:self.backgroundImage];
    [self.view sendSubviewToBack:self.backgroundImage];
}

- (void)setBarPreferences
{
    UIColor *color = [UIColor colorWithRed:209.0/255.0 green:8.0/255.0 blue:109.0/255.0 alpha:1];
    self.navigationController.navigationBar.tintColor = color;
}

-(void)addCollView
{
    [collectionView setDataSource:self];
    [collectionView setDelegate:self];
    // Configure layout
    UICollectionViewFlowLayout *flowLayout = (UICollectionViewFlowLayout*)collectionView.collectionViewLayout;;
    [flowLayout setItemSize:CGSizeMake(762, 112)];
    [flowLayout setScrollDirection:UICollectionViewScrollDirectionVertical];
    flowLayout.minimumInteritemSpacing = 1000.0f;
    flowLayout.minimumLineSpacing = 0.0f;
    flowLayout.sectionInset = UIEdgeInsetsMake(20, 0, 20, 0);
    flowLayout.headerReferenceSize = flowLayout.itemSize;

    [collectionView setCollectionViewLayout:flowLayout];
    [collectionView setBackgroundColor:[UIColor clearColor]];
    [collectionView registerClass:[ExCell class] forCellWithReuseIdentifier:@"ExCell"];
    [collectionView registerClass:[HeaderView class] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"HeaderView"];

    [self.view addSubview:collectionView];
}

- (void)loadData
{
    ExerciseDatabase *database = [[ExerciseDatabase alloc ] init];
    NSArray *exerciseInfos = database.exerciseInfos;
    titles = [[NSMutableArray alloc]init];
    enonces = [[NSMutableArray alloc]init];
    subtitles = [[NSMutableArray alloc]init];
    parts = [[NSMutableArray alloc]init];
    numbers = [[NSMutableArray alloc]init];
    int n=1;
    nbSections =-1;

    for (Exercise *exercise in exerciseInfos) {
        [titles addObject:exercise.title];
        [numbers addObject:[NSString stringWithFormat:@"%d",exercise.num]];
        [subtitles addObject:exercise.subtitle];
        [enonces addObject:exercise.enonce];
        NSArray *partsArray = [parts copy];

        if(![partsArray containsObject:exercise.header]) {
            [parts addObject:exercise.header];
            nbSections++;
            n = 1;
        } else {
            n++;
        }

        nbItemsInPart[nbSections] = n;
    }
}

#pragma mark - UICollectionView Datasource
- (NSInteger)collectionView:(UICollectionView *)view numberOfItemsInSection:(NSInteger)section
{
    //section commence à 0.
    NSLog(@"%ld",nbItemsInPart[section]);
    return nbItemsInPart[section];
}

- (NSInteger)numberOfSectionsInCollectionView: (UICollectionView *)collectionView
{
    return (nbSections+1);
}

// creates the individual cells to go in the menu view
- (ExCell*) collectionView:(UICollectionView *)collectView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
    //create collection view cell
    ExCell *cell = (ExCell *)[collectView dequeueReusableCellWithReuseIdentifier:@"ExCell" forIndexPath:indexPath];

    // the index is the row number in section + the number of items in all previous sections
    int index = (int)indexPath.row;
    for(int k=0; k < indexPath.section ; k++) {
        index += nbItemsInPart[k];
    }

    //configure cell :
    NSMutableString *text = [[NSMutableString alloc]initWithString:@"Practical Exercise "];
    [text appendString:[NSString stringWithFormat:@"%d",index+1]];
    [text appendString:@"\n"];
    [text appendString:[titles objectAtIndex:index]];
    cell.label.text = text;
    [cell.reminder addTarget:self action:@selector(doSomething:) forControlEvents: UIControlEventTouchUpInside];
    [cell.done addTarget:self action:@selector(checked:) forControlEvents:UIControlEventTouchUpInside];
    // set tag to the indexPath.row so we can access it later
    [cell setTag:index];

    // return the cell
    return cell;
}

- (UICollectionReusableView *)collectionView:(UICollectionView *)collectView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath
{
    HeaderView *headerView = [collectView dequeueReusableSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"HeaderView" forIndexPath:indexPath];
    NSMutableString *text = [[NSMutableString alloc]initWithString:@" "];
    [text appendString:[parts objectAtIndex:indexPath.section]];
    headerView.label.text = text;

    return headerView;
}

-(IBAction)doSomething:(id) sender
{
    [self performSegueWithIdentifier:@"reminder" sender:self];
}

-(void)checked:(id)sender
{
    if([sender imageForState:UIControlStateNormal] == [UIImage imageNamed:@"checked.png"]) {
        [sender setImage:[UIImage imageNamed:@"unchecked.png"] forState:UIControlStateNormal];
    } else {
        [sender setImage:[UIImage imageNamed:@"checked.png"] forState:UIControlStateNormal];
    }
}

@end

这是我自定义标题单元格的代码：

#import "HeaderView.h"
@implementation HeaderView

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        self.label = [[UILabel alloc] initWithFrame:self.frame];
        NSLog(@"created label");
        self.label.backgroundColor = [UIColor colorWithWhite:0.2 alpha:0.5];
        [self addSubview:self.label];
    }
    return self;
}

---

看起来像：

Answer 1

不使用self.frame作为初始框架，而是使用self.bounds

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        self.label = [[UILabel alloc] initWithFrame:self.bounds];
        NSLog(@"created label");
        self.label.backgroundColor = [UIColor colorWithWhite:0.2 alpha:0.5];
        [self addSubview:self.label];
    }
    return self;
}