TableView Cell的展开与收缩,动态计算高度

先看tableView中代码

//
//  ViewController.m
//  JActivityList
//
//  Created by juanmao on 15/12/6.
//  Copyright © 2015年 juanmao. All rights reserved.
//

#import "ViewController.h"
#import "TextEntity.h"
#import "TextListCell.h"
#define kWidth            [UIScreen mainScreen].bounds.size.width
#define kHeight           [UIScreen mainScreen].bounds.size.height
@interface ViewController ()
@property(nonatomic, strong)UITableView      *mTabelView;
@property(nonatomic, strong)NSMutableArray   *dataArr;
@property(nonatomic,assign) BOOL flag;
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor whiteColor];
    self.title = @"举个";
    self.dataArr = [NSMutableArray array];
    [self initData];
    [self addSubView];
    
}

- (void)addSubView
{
    self.mTabelView = [[UITableView alloc]initWithFrame:CGRectMake(0, 0,kWidth,kHeight) style:UITableViewStylePlain];
    self.mTabelView.delegate = self;
    self.mTabelView.dataSource = self;
    self.mTabelView.tableFooterView  = [UIView new];
    [self.view addSubview:self.mTabelView];
}

/*!
 *    解析本地json数据
 */
- (void)initData
{
    NSString *path=[[NSBundle mainBundle] pathForResource:@"TextInfo" ofType:@"json"];
    NSString *jsonContent=[[NSString alloc] initWithContentsOfFile:path encoding:NSUTF8StringEncoding error:nil];
    if (jsonContent != nil)
    {
        NSData *jsonData = [jsonContent dataUsingEncoding:NSUTF8StringEncoding];
        NSError *err;
        NSMutableDictionary *dic = [NSJSONSerialization JSONObjectWithData:jsonData
                                                                   options:NSJSONReadingMutableContainers
                                                                     error:&err];
        NSArray *textList = [dic objectForKey:@"textList"];
        for (NSDictionary *dict in textList)
        {
            TextEntity *entity = [[TextEntity alloc]initWithDict:dict];
            if (entity)
            {
                [self.dataArr addObject:entity];
            }
        }
        if(err)
        {
            NSLog(@"json解析失败：%@",err);
        }
    }
}

#pragma  mark UITableViewDataSource
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    return [self.dataArr count];
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *identifier = @"cell";
    TextListCell *cell = (TextListCell *)[tableView dequeueReusableCellWithIdentifier:identifier];
    if (!cell){
        cell = [[TextListCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:identifier];
        cell.selectionStyle = UITableViewCellSelectionStyleNone;
    }
    if ([self.dataArr count] > indexPath.row){
            //这里的判断是为了防止数组越界
         cell.entity = [self.dataArr objectAtIndex:indexPath.row];
    }
        //自定义cell的回调，获取要展开/收起的cell。刷新点击的cell
    cell.showMoreTextBlock = ^(UITableViewCell *currentCell){
        [self.mTabelView reloadRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationAutomatic];
    };

    return cell;

}

#pragma mark UITableViewDelegate
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath{
    TextEntity *entity = nil;
    if ([self.dataArr count] > indexPath.row)
    {
        entity = [self.dataArr objectAtIndex:indexPath.row];
    }
        //根据isShowMoreText属性判断cell的高度
    if (entity.isShowMoreText)
    {
        return [TextListCell cellMoreHeight:entity];
    }
    else
    {
        return [TextListCell cellDefaultHeight:entity];
    }
    return 0;
}
@end

核心代码是 点了cell上的按钮后重新刷新改行cell,并重新计算cell高度

[self.mTabelView reloadRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationAutomatic];

以下是cell中的代码

//
//  TextListCell.m
//  JActivityList
//
//  Created by juanmao on 15/12/7.
//  Copyright © 2015年 juanmao. All rights reserved.
//
#define kWidth            [UIScreen mainScreen].bounds.size.width
#import "TextListCell.h"
@interface TextListCell()
{
    UILabel      *_textTitle;
    UILabel      *_textContent;
    UIButton     *_moreTextBtn;
}
@end


@implementation TextListCell

+ (CGFloat)cellDefaultHeight:(TextEntity *)entity
{
        //默认cell高度
    return 85.0;
}

+ (CGFloat)cellMoreHeight:(TextEntity *)entity
{
    //展开后得高度(计算出文本内容的高度+固定控件的高度)
    NSDictionary *attribute = @{NSFontAttributeName: [UIFont systemFontOfSize:16]};
    NSStringDrawingOptions option = (NSStringDrawingOptions)(NSStringDrawingTruncatesLastVisibleLine | NSStringDrawingUsesLineFragmentOrigin | NSStringDrawingUsesFontLeading);
    CGSize size = [entity.textContent boundingRectWithSize:CGSizeMake(kWidth - 30, 100000) options:option attributes:attribute context:nil].size;;
    return size.height + 50;
}

- (id)initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(NSString *)reuseIdentifier
{
    self = [super initWithStyle:style reuseIdentifier:reuseIdentifier];
    if (self)
    {
        _textTitle = [[UILabel alloc]initWithFrame:CGRectMake(15, 5, 140, 20)];
        _textTitle.textColor = [UIColor blackColor];
        _textTitle.font = [UIFont systemFontOfSize:18];
        [self.contentView addSubview:_textTitle];
        
        _textContent = [[UILabel alloc]initWithFrame:CGRectMake(15, 30,kWidth - 30 , 20)];
        _textContent.textColor = [UIColor blackColor];
        _textContent.font = [UIFont systemFontOfSize:16];
        _textContent.numberOfLines = 0;
        [self.contentView addSubview:_textContent];
        
        _moreTextBtn = [UIButton buttonWithType:UIButtonTypeCustom];
        [_moreTextBtn setTitleColor:[UIColor grayColor] forState:UIControlStateNormal];
        _moreTextBtn.frame = CGRectMake(kWidth - 50, 5, 40, 20);
        [self.contentView addSubview:_moreTextBtn];
        [_moreTextBtn addTarget:self action:@selector(showMoreText) forControlEvents:UIControlEventTouchUpInside];
        
    }
    return self;
}

- (void)layoutSubviews
{
    [super layoutSubviews];
    _textTitle.text = self.entity.textName;
    
    _textContent.text = self.entity.textContent;
    if (self.entity.isShowMoreText)
    {
            ///计算文本高度
        NSDictionary *attribute = @{NSFontAttributeName: [UIFont systemFontOfSize:16]};
        NSStringDrawingOptions option = (NSStringDrawingOptions)(NSStringDrawingTruncatesLastVisibleLine | NSStringDrawingUsesLineFragmentOrigin | NSStringDrawingUsesFontLeading);
        CGSize size = [self.entity.textContent boundingRectWithSize:CGSizeMake(kWidth - 30, 100000) options:option attributes:attribute context:nil].size;
        [_textContent setFrame:CGRectMake(15, 30, kWidth - 30, size.height)];
        
        [_moreTextBtn setTitle:@"收起" forState:UIControlStateNormal];
    }
    else
    {
        [_moreTextBtn setTitle:@"展开" forState:UIControlStateNormal];
        [_textContent setFrame:CGRectMake(15, 30, kWidth - 30, 35)];
    }
    
}

- (void)showMoreText
{
        //将当前对象的isShowMoreText属性设为相反值
    self.entity.isShowMoreText = !self.entity.isShowMoreText;
    if (self.showMoreTextBlock)
    {
        self.showMoreTextBlock(self);
    }
}
@end

重点是计算高度部分

+ (CGFloat)cellMoreHeight:(TextEntity *)entity
{
    //展开后得高度(计算出文本内容的高度+固定控件的高度)
    NSDictionary *attribute = @{NSFontAttributeName: [UIFont systemFontOfSize:16]};
    NSStringDrawingOptions option = (NSStringDrawingOptions)(NSStringDrawingTruncatesLastVisibleLine | NSStringDrawingUsesLineFragmentOrigin | NSStringDrawingUsesFontLeading);
    CGSize size = [entity.textContent boundingRectWithSize:CGSizeMake(kWidth - 30, 100000) options:option attributes:attribute context:nil].size;;
    return size.height + 50;
}