Question

我遇到了一个问题。当我将以下代码实现到tableViewController时我没有问题，它显示扩展/收缩表就好了。但是，当我尝试将代码实现到viewController中的tableView时，它将不会显示。有什么想法吗？我已经在我的.h文件中包含了tableview委托和数据源文件。

这是头文件：

#import <UIKit/UIKit.h>

 @interface MainViewController : UIViewController <UITableViewDataSource, UITableViewDelegate>
{
NSArray *topItems;
NSMutableArray *subItems; // array of arrays

int currentExpandedIndex;
}

@property (weak, nonatomic) IBOutlet UITableView *tableView;



@end

这是.m文件

#import "MainViewController.h"
#define NUM_TOP_ITEMS 20
#define NUM_SUBITEMS 6


@interface MainViewController ()

@end


@implementation MainViewController


- (id)init {
self = [super init];

if (self) {
    topItems = [[NSArray alloc] initWithArray:[self topLevelItems]];
    subItems = [NSMutableArray new];
    currentExpandedIndex = -1;

    for (int i = 0; i < [topItems count]; i++) {
        [subItems addObject:[self subItems]];
    }
}
return self;
}

#pragma mark - Data generators

- (NSArray *)topLevelItems {
NSMutableArray *items = [NSMutableArray array];

for (int i = 0; i < NUM_TOP_ITEMS; i++) {
    [items addObject:[NSString stringWithFormat:@"Item %d", i + 1]];
}

return items;
}

- (NSArray *)subItems {
NSMutableArray *items = [NSMutableArray array];
int numItems = arc4random() % NUM_SUBITEMS + 2;

for (int i = 0; i < numItems; i++) {
    [items addObject:[NSString stringWithFormat:@"SubItem %d", i + 1]];
}

return items;
}

#pragma mark - View management

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

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
return (interfaceOrientation == UIInterfaceOrientationPortrait);
}

#pragma mark - Table view data source

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

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
return [topItems count] + ((currentExpandedIndex > -1) ? 
[[subItems      objectAtIndex:currentExpandedIndex] count] : 0);
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:
(NSIndexPath      *)indexPath {
static NSString *ParentCellIdentifier = @"ParentCell";
static NSString *ChildCellIdentifier = @"ChildCell";

BOOL isChild =
currentExpandedIndex > -1
&& indexPath.row > currentExpandedIndex
&& indexPath.row <= currentExpandedIndex + 
[[subItems objectAtIndex:currentExpandedIndex]   count];

UITableViewCell *cell;

if (isChild) {
    cell = [tableView dequeueReusableCellWithIdentifier:ChildCellIdentifier];
}
else {
    cell = [tableView dequeueReusableCellWithIdentifier:ParentCellIdentifier];
}


if (cell == nil) {
    cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:ParentCellIdentifier];
}

if (isChild) {
    cell.detailTextLabel.text = 
[[subItems objectAtIndex:currentExpandedIndex] 
objectAtIndex:indexPath.row - currentExpandedIndex - 1];
}
else {
    int topIndex = (currentExpandedIndex > -1 && indexPath.row > currentExpandedIndex)
    ? indexPath.row - [[subItems objectAtIndex:currentExpandedIndex] count]
    : indexPath.row;

    cell.textLabel.text = [topItems objectAtIndex:topIndex];
    cell.detailTextLabel.text = @"";
}

return cell;
}

#pragma mark - Table view delegate

 - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
BOOL isChild =
currentExpandedIndex > -1
&& indexPath.row > currentExpandedIndex
&& indexPath.row <= currentExpandedIndex + 
[[subItems objectAtIndex:currentExpandedIndex] count];

if (isChild) {
    NSLog(@"A child was tapped, do what you will with it");
    return;
}

[self.tableView beginUpdates];

if (currentExpandedIndex == indexPath.row) {
    [self collapseSubItemsAtIndex:currentExpandedIndex];
    currentExpandedIndex = -1;
}
else {

    BOOL shouldCollapse = currentExpandedIndex > -1;

    if (shouldCollapse) {
        [self collapseSubItemsAtIndex:currentExpandedIndex];
    }

    currentExpandedIndex = (shouldCollapse && indexPath.row > currentExpandedIndex) ? indexPath.row - [[subItems objectAtIndex:currentExpandedIndex] count] : indexPath.row;

    [self expandItemAtIndex:currentExpandedIndex];
}

[self.tableView endUpdates];

}

- (void)expandItemAtIndex:(int)index {
NSMutableArray *indexPaths = [NSMutableArray new];
NSArray *currentSubItems = [subItems objectAtIndex:index];
int insertPos = index + 1;
for (int i = 0; i < [currentSubItems count]; i++) {
    [indexPaths addObject:[NSIndexPath indexPathForRow:insertPos++ inSection:0]];
}
[self.tableView insertRowsAtIndexPaths:indexPaths withRowAnimation:UITableViewRowAnimationFade];
[self.tableView scrollToRowAtIndexPath:
[NSIndexPath indexPathForRow:index inSection:0]  
atScrollPosition:UITableViewScrollPositionTop animated:YES];

}

 - (void)collapseSubItemsAtIndex:(int)index {
NSMutableArray *indexPaths = [NSMutableArray new];
for (int i = index + 1; i <= index + [[subItems objectAtIndex:index] count]; i++) {
    [indexPaths addObject:[NSIndexPath indexPathForRow:i inSection:0]];
}
[self.tableView deleteRowsAtIndexPaths:indexPaths withRowAnimation:UITableViewRowAnimationFade];

}
@end

Answer 1

您需要在viewDidLoad或XIB中设置委托和数据源。

在代码中：

[self.tableView setDelegate:self];
[self.tableView setDataSource:self];

在您的控制器中：

- (void)viewDidLoad {
    [super viewDidLoad];
    [self.tableView setDelegate:self];
    [self.tableView setDataSource:self];
}

tableView数据未显示

1 个答案: