tableView点击下拉更多的效果

r囧r小猫 2021-11-26 10:18 299阅读 0赞

tableView点击下拉查看更多，主要原理就是在tableView的didSelect方法里插入(更多)或者删除(回收)一定数量的cell。

本例子是用section作为单位来分块。个人感觉这种方式是最方便的。

其中用到了一个二维数组（数据源），一个一维数组，用于存放每个section的状态。

头文件如下：

#import <UIKit/UIKit.h>
    
    @interface MainViewController : UITableViewController{
        NSMutableArray *_nameArray;
        NSMutableArray *boolArray;
    }
    
    @property (nonatomic, retain) NSMutableArray *nameArray;
    
    @end

实现文件如下：

#import "MainViewController.h"
    
    @interface MainViewController ()
    
    @end
    
    @implementation FNDMainViewController
    //@synthesize nameArray = _nameArray;
    
    #pragma mark - lifeCycle methods
    - (id)initWithStyle:(UITableViewStyle)style
    {
        self = [super initWithStyle:style];
        if (self) {
            _nameArray = [[NSMutableArray alloc] init];
            NSArray *array1 = [NSArray arrayWithObjects:@"1",@"2",@"3",@"4",@"5", nil];
            NSArray *array2 = [NSArray arrayWithObjects:@"a",@"b",@"c",@"d",@"e",@"f",@"g", nil];
            NSArray *array3 = [NSArray arrayWithObjects:@"liu",@"ping",@"wei",@"ni",@"hao",@"haha",@"your", nil];
            NSArray *array4 = [NSArray arrayWithObjects:@"apple",@"banana",@"orange",@"give",@"me",@"off",@"up", nil];
            /*
            NSArray *array5 = [NSArray arrayWithObjects:@"1",@"2",@"3",@"4",@"5", nil];
            NSArray *array6 = [NSArray arrayWithObjects:@"a",@"b",@"c",@"d",@"e",@"f",@"g", nil];
            NSArray *array7 = [NSArray arrayWithObjects:@"liu",@"ping",@"wei",@"ni",@"hao",@"haha",@"your", nil];
            NSArray *array8 = [NSArray arrayWithObjects:@"apple",@"banana",@"orange",@"give",@"me",@"off",@"up", nil];
            NSArray *array9 = [NSArray arrayWithObjects:@"you",@"me", nil];
             */
            
            [_nameArray addObject:array1];
            [_nameArray addObject:array2];
            [_nameArray addObject:array3];
            [_nameArray addObject:array4];
            /*
            [_nameArray addObject:array5];
            [_nameArray addObject:array6];
            [_nameArray addObject:array7];
            [_nameArray addObject:array8];
            [_nameArray addObject:array9];
             */
    
        }
        return self;
    }
    
    - (void)viewDidLoad
    {
    
        [super viewDidLoad];
        boolArray = [[NSMutableArray alloc] init];
        //YES为拉伸  NO为收缩
        for (int i = 0; i < self.nameArray.count; i++) {
            [boolArray addObject:@"no"];
        }
    }
    
    #pragma mark - manage memory metohds
    
    - (void)didReceiveMemoryWarning
    {
        [super didReceiveMemoryWarning];
    }
    
    -(void)viewWillAppear:(BOOL)animated{
        [super viewWillAppear:animated];
    }
    
    -(void)dealloc{
        boolArray = nil;
        [boolArray release];
        _nameArray = nil;
        [_nameArray release];
        [super dealloc];
    }
    #pragma mark - Table view data source
    
    - (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
    {
        //return [_nameArray count];
        return self.nameArray.count;
    }
    
    - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
    {
        if ([boolArray[section] isEqualToString: @"yes"]) {
            return [[_nameArray objectAtIndex:section] count];
        }else{
            return 2;
        }
        
    }
    
    - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
    {
        static NSString *CellIdentifier = @"Cell";
        UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
        
        if (cell == nil) {
            cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
        }
        //如果本section对应的数组成员数大于本section的行数，则说明是收缩状态
        if ([[_nameArray objectAtIndex:indexPath.section] count] > indexPath.row) {
            cell.textLabel.text = [[_nameArray objectAtIndex:indexPath.section] objectAtIndex:indexPath.row];
        }
        //如果本section对应的状态为no,并且本行为本section的第二行，并且本section对应的内容数组成员不等于2则说 明是收缩状态，将第二行的textLabel改为@"更多"
        if ([boolArray[indexPath.section] isEqualToString: @"no"] &&indexPath.row == 1 &&
            [[self.nameArray objectAtIndex:indexPath.section] count] != 2) {
            cell.textLabel.text = nil;
            cell.textLabel.text = @"更多";
        }
        return cell;
    }
    
    
    #pragma mark - Table view delegate
    
    - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
    {
        //改变选择的状态
        [tableView deselectRowAtIndexPath:indexPath animated:YES];
        NSMutableArray *array = [[NSMutableArray alloc] init];
        UITableViewCell *cell = [tableView cellForRowAtIndexPath:[NSIndexPath indexPathForRow:1 inSection:indexPath.section]];
        //如果选中行所在的section为收缩状态
        if ([boolArray[indexPath.section] isEqualToString: @"no"]) {
            //改变状态值
            boolArray[indexPath.section] = @"yes";
            //把更多修改为数组里对应的值
            cell.textLabel.text = [[self.nameArray objectAtIndex:indexPath.section]objectAtIndex:1];
            //关键部分
            for (int i = 2; i < [[_nameArray objectAtIndex:indexPath.section] count]; i++) {
                NSIndexPath *index = [NSIndexPath indexPathForRow:i inSection:indexPath.section];
                [array addObject:index];
            }
            
            [self.tableView insertRowsAtIndexPaths:array withRowAnimation:UITableViewRowAnimationFade];
            
        }else{
            //如果为拉伸状态，把状态改为收缩
            boolArray[indexPath.section] = @"no";
            //把第二行改为@“更多”
            cell.textLabel.text = @"More";
            for (int i = 2; i < [[_nameArray objectAtIndex:indexPath.section] count]; i++){
                NSIndexPath *index = [NSIndexPath indexPathForRow:i inSection:indexPath.section];
                [array addObject:index];
            }
            [self.tableView deleteRowsAtIndexPaths:array                          withRowAnimation:UITableViewRowAnimationFade];
        }
        [array release];
    }
    
    -(NSIndexPath *)tableView:(UITableView *)tableView willSelectRowAtIndexPath:(NSIndexPath *)indexPath{
        //如果这个section的cell只有2个，丫的返回nil
        if ([[self.nameArray objectAtIndex:indexPath.section] count] == 2) {
            return nil;
        }
        //判断是否为收缩状态
        if ([boolArray[indexPath.section] isEqualToString: @"yes"]) {
                return indexPath;
        }else{
            //如果为收缩状态，判断点击的行数是否为第二行（更多），如果不是点第二行(更多)，则返回nil
            if (indexPath.row == 1) {
                return indexPath;
            }else{
                //NSLog(@"收缩状态，不是点更多");
                return nil;
            }
        }
        
    }
    
    @end