UITableViewCell的一些优化

Contents

1. 1. 编写一个自定义UITableViewCell的基本步骤
2. 2. 先记录一个简单的Cell编写步骤
3. 3. 再看一个使用FrameModel来缓存Cell高度的例子
4. 4. 使用AutoLayout形式的cell高度计算
5. 5. Cell之间做一些间隙

编写一个自定义UITableViewCell的基本步骤

新建一个UITableViewCell子类

重写initWithStyle:方法

创建所有的UI Subviews实例
将所有的subviews实例添加到UITableViewCell.contentView
对一些subview设置基础属性（字体大小、字体名、字体颜色、背景色..）
提供两个模型

模型1 >>> 实体类:
存储Cell上所有subviews显示需要的数据，来决定某些subview是显示or隐藏
模型2 >>> Frame:
存储Cell显示的frame大小，主要是高度
UITableViewDelegate的高度回调函数返回cell的高度时

返回Cell位置对应的Frame模型记录的高度
做了一个Cell的高度缓存

先记录一个简单的Cell编写步骤

首先是先写一个Base基类Cell，提供一些给子类Cell重写的模板方法.

#import <UIKit/UIKit.h>

@interface BaseCell : UITableViewCell

/**

• 传入TableView查询一个cell对象，该identifier由各自Cell类自己管理，不向外暴露
  */

• (instancetype)dequeFromTableView:(UITableView *)tableView;

/**

• 传入实体类对象，设置subviews的数据显示
  */

• (void)setupData:(id)data;

/**

• 初始化subviews
  */

• (void)setupSubviews;

@end

#import “BaseCell.h”

@implementation BaseCell

//子类实现

• (instancetype)dequeFromTableView:(UITableView *)tableView {return nil;}

//子类实现

• (void)setupData:(id)data {}

//子类实现

• (void)setupSubviews {}

• (instancetype)initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(NSString *)reuseIdentifier {
  if (self = [super initWithStyle:style reuseIdentifier:reuseIdentifier]) {
  [self setupSubviews];
  }
  return self;
  }

@end
然后看写一个子类Cell.

#import “BaseCell.h”

@interface NewsCell : BaseCell

@end

#import “NewsCell.h”

//导入cell依赖的实体类

#import “News.h”

@interface NewsCell ()

@property (nonatomic, strong) UILabel titleLabel;
@property (nonatomic, strong) UILabel contentLabel;

@end

@implementation NewsCell

• (instancetype)dequeFromTableView:(UITableView )tableView {
  NewsCell cell = [tableView dequeueReusableCellWithIdentifier:@”mycell”];
  if (!cell) {
  cell = [[NewsCell alloc] initWithStyle:UITableViewCellStyleValue2 reuseIdentifier:@”mycell”];
  }
  return cell;
  }

• (void)setupSubviews {
  _titleLabel = [UILabel new];
  _contentLabel = [UILabel new];

_titleLabel.font = [UIFont systemFontOfSize:16.0f];
_contentLabel.font = [UIFont systemFontOfSize:16.0f];

[self.contentView addSubview:_titleLabel];
[self.contentView addSubview:_contentLabel];
}

• (void)setupData:(id)data {
  //1.
  if ([data isEqual:[NSNull null]]) return;
  if (![data isKindOfClass:[News class]]) return;

//2.
News news = (News )data;

//3.
_titleLabel.text = news.title;
_contentLabel.text = news.content;

//4. 通知重新计算cell内部所有subview的frame
[self setNeedsLayout];
}

#pragma mark - 重用时清除之前的数据

• (void)prepareForReuse {
  [super prepareForReuse];

_titleLabel.text = @””;
_contentLabel.text = @””;
}

#pragma mark - frame布局

• (void)layoutSubviews {
  [super layoutSubviews];

/ 下面对所有的subviews进行frame布局 /

//titleLabel的frame
CGFloat x = 10;
CGFloat y = 10;
CGFloat w = CGRectGetWidth(self.frame);
CGFloat h = CGRectGetHeight(self.frame) * 0.3;
_titleLabel.frame = CGRectMake(x, y, w, h);

//contentLabel的frame
x = 10;
y = CGRectGetMaxY(_titleLabel.frame) + 10;
w = CGRectGetWidth(self.frame);
h = CGRectGetHeight(self.frame) (1 - 0.3) - 10 2;
_contentLabel.frame = CGRectMake(x, y, w, h);
}

@end
上面的例子比较简单的，是需要Cell自己内部计算所有subviews的frame。下面给出一种比较好的优化思路，将计算cell内部所有subviews的frame代码单独使用一个类对象来封装，这样做的好处:

Cell自己不再计算内部subviews的frame
不用Cell自己每次调用setNeedLayout重新计算设置subviews的frame
由外部对象计算frame，并缓存起来，下一次直接传入对应实体对象的frame模型即可，避免多次重复计算subviews的frame

再看一个使用FrameModel来缓存Cell高度的例子

Cell依赖的实体类Statuses

#import <Foundation/Foundation.h>

//依赖User实体类

#import “User.h”

@interface Statuses : NSObject

@property (nonatomic, copy) NSString *idstr;

@property (nonatomic, strong) NSNumber attitudes_count;
@property (nonatomic, strong) NSNumber biz_feature;
@property (nonatomic, strong) NSNumber comments_count;
@property (nonatomic, strong) NSNumber favorited;
@property (nonatomic, strong) NSNumber *reposts_count;

@property (nonatomic, copy) NSString created_at;
@property (nonatomic, copy) NSString text;
@property (nonatomic, copy) NSString *source;

@property (nonatomic, copy) NSString thumbnail_pic;
@property (nonatomic, copy) NSString bmiddle_pic;
@property (nonatomic, copy) NSString *original_pic;

@property (nonatomic, strong) User *user;

//来自的转发微博
@property (nonatomic, strong) Statuses *retweeted_status;

//配图数组
@property (nonatomic, strong) NSArray *pic_urls;

/**

• 拼接得到转发微博的内容
  */

• (NSString *)retweetContent;

@end

#import <Foundation/Foundation.h>

@interface User : NSObject

@property (nonatomic, copy) NSString idstr;
@property (nonatomic, strong) NSNumber mbtype;
@property (nonatomic, strong) NSNumber mbrank;
@property (nonatomic, copy) NSString screen_name;
@property (nonatomic, copy) NSString name;
@property (nonatomic, copy) NSString location;
@property (nonatomic, copy) NSString url;
@property (nonatomic, copy) NSString profile_image_url;
@property (nonatomic, copy) NSString cover_image;
@property (nonatomic, copy) NSString cover_image_phone;
@property (nonatomic, copy) NSString profile_url;
@property (nonatomic, copy) NSString domain;
@property (nonatomic, strong) NSNumber followers_count;
@property (nonatomic, strong) NSNumber friends_count;
@property (nonatomic, strong) NSNumber favourites_count;
@property (nonatomic, copy) NSString created_at;
@property (nonatomic, copy) NSString avatar_large;
@property (nonatomic, copy) NSString avatar_hd;
@property (nonatomic, copy) NSString *verified_reason;

//添加一个vip变量，并且提供一个get方法叫做isVip
@property (nonatomic, assign, getter = isVip) BOOL vip;

@end
创建一个FrameModel实体类专门负责计算一个实体类Statuses的对象显示在一个Cell内部所有subviews显示的frame，以及Cell的总高度.

#import <Foundation/Foundation.h>

#import <UIKit/UIKit.h>

#import “Statuses.h”

#define padding 10

#define NameFont [UIFont systemFontOfSize:13.f]

#define TimeFont [UIFont systemFontOfSize:12.f]

#define ContentFont [UIFont systemFontOfSize:14.f]

/**

• 这个模型类的职责:
  *
• 1. 承载实体类模型Statuses实例
• 2. 计算负责显示Statuses实例对应的TableViewCell需要的frame
• 2.1 TableViewCell内部所有subviews显示的frame
• 2.2 TableViewCell自己显示的总高度
• 3. 所有的frame基于[UIScreen mainScreen].bounds.size计算
     /
     @interface StatusFrameModel : NSObject

//实体类模型
@property (nonatomic, strong) Statuses *status;

//对应subview显示数据的frame
@property (nonatomic, assign) CGRect iconImageViewFrame;
@property (nonatomic, assign) CGRect vipImageViewFrame;
@property (nonatomic, assign) CGRect photoImageViewFrame;
@property (nonatomic, assign) CGRect nameLabelFrame;
@property (nonatomic, assign) CGRect timeLabelFrame;
@property (nonatomic, assign) CGRect sourceLabelFrame;
@property (nonatomic, assign) CGRect contentLabelFrame;
@property (nonatomic, assign) CGRect contentContainerFrame;

@property (nonatomic, assign) CGRect retweetContainerFrame;
@property (nonatomic, assign) CGRect retweetContentLabelFrame;
@property (nonatomic, assign) CGRect retweetImageViewFrame;

@property (nonatomic, assign) CGRect bottomContainerFrame;

//最终cell的高度
@property (nonatomic, assign) CGFloat cellHeight;

@end

#import “StatusFrameModel.h”

#import “NSString+Extension.h”

@implementation StatusFrameModel

/**

• 重写setter实体类对象方法，计算实体类对象在cell上显示的所有frame以及总高度
  */

• (void)setStatus:(Statuses *)status {

_status = status;

/**

• 计算所有数据项显示在cell上时对应的frame
  *
• 规则1. 从上到下，累计计算
• 规则2. 从左到右，累计计算
  */

User *user = status.user;

//头像frame
CGFloat iconWH = 50;
CGFloat iconX = padding;
CGFloat iconY = padding;
_iconImageViewFrame = CGRectMake(iconX, iconY, iconWH, iconWH);

//昵称
CGFloat nameX = CGRectGetMaxX(_iconImageViewFrame) + padding;
CGFloat nameY = iconY;
CGSize nameSize = [user.name sizeWithfont:NameFont];
_nameLabelFrame = CGRectMake(nameX, nameY, nameSize.width, nameSize.height);

//Vip图像
if ([user isVip]) {//如果是会员才设置Vip图像
CGFloat vipX = CGRectGetMaxX(_nameLabelFrame) + padding;
CGFloat vipY = nameY;
CGFloat vipW = 14;
CGFloat vipH = nameSize.height;
_vipImageViewFrame = CGRectMake(vipX, vipY , vipW, vipH);
}

//时间
CGFloat timeX = nameX;
CGFloat timeY = CGRectGetMaxY(_nameLabelFrame) + padding;
CGSize timeSize = [status.created_at sizeWithfont:TimeFont];
_timeLabelFrame = CGRectMake(timeX, timeY, timeSize.width, timeSize.height);

//来源
CGFloat sourX = CGRectGetMaxX(_timeLabelFrame) + padding;
CGFloat sourY = timeY;
CGSize sourSize = [status.created_at sizeWithfont:TimeFont];
_sourceLabelFrame = CGRectMake(sourX, sourY, sourSize.width, sourSize.height);

//正文
CGFloat contentX = iconX;
CGFloat contentY = MAX(CGRectGetMaxY(_timeLabelFrame), CGRectGetMaxY(_iconImageViewFrame)) + padding;
CGFloat contentW = [UIScreen mainScreen].bounds.size.width - 2 * contentX;
CGFloat contentH = [status.text sizeWithfont:ContentFont MaxWidth:contentW].height;
_contentLabelFrame = CGRectMake(contentX, contentY, contentW, contentH);

//配图
BOOL isHasPhotos = status.pic_urls.count > 0;

if (isHasPhotos) {
CGFloat photoX = iconX;
CGFloat photoY = CGRectGetMaxY(_contentLabelFrame) + padding;
CGSize photoSize = [WeiboPhotoView photoViewSizeWithPhotoCount:status.pic_urls.count];

_photoImageViewFrame = CGRectMake(photoX, photoY, photoSize.width, photoSize.height);

} else {

//如果实体类数据没有这个subview显示的数据项
_photoImageViewFrame = CGRectZero;
}

//顶部和中间的容器
CGFloat containerMiddleX = 0;
CGFloat containerMiddleY = 0;
CGFloat containerMiddleW = [UIScreen mainScreen].bounds.size.width;
CGFloat containerMiddleH;

if (!isHasPhotos) {
containerMiddleH = CGRectGetMaxY(_contentLabelFrame) + padding;
} else {
containerMiddleH = CGRectGetMaxY(_photoImageViewFrame) + padding;
}

_contentContainerFrame = CGRectMake(containerMiddleX, containerMiddleY, containerMiddleW, containerMiddleH);

//转发微博
BOOL isHasRetweet = (status.retweeted_status != nil);

if (isHasRetweet) {//存在转发微博

//转发微博正文
CGFloat retweetContentX = padding;
CGFloat retweetContentY = padding;
CGFloat retweetContentW = [UIScreen mainScreen].bounds.size.width - 2 * padding;
CGFloat retweetContentH = [[status retweetContent] sizeWithfont:ContentFont MaxWidth:retweetContentW].height;

_retweetContentLabelFrame = CGRectMake(retweetContentX, retweetContentY, retweetContentW, retweetContentH);

//转发微博图片
BOOL isHasRetweetImage = (status.retweeted_status.pic_urls.count > 0);

if (isHasRetweetImage) {//有微博配图
CGFloat retweetImageX = retweetContentX;
CGFloat retweetImageY = CGRectGetMaxY(_retweetContentLabelFrame) + padding;
CGSize retweetImageSize = [WeiboPhotoView photoViewSizeWithPhotoCount:status.retweeted_status.pic_urls.count];

_retweetImageViewFrame = CGRectMake(retweetImageX, retweetImageY, retweetImageSize.width, retweetImageSize.height);
} else {

//如果实体类数据没有这个subview显示的数据项
_retweetImageViewFrame = CGRectZero;
}

//转发微博容器
CGFloat retweetContainerX = 0;
CGFloat retweetContainerW = [UIScreen mainScreen].bounds.size.width;
CGFloat retweetContainerY = CGRectGetMaxY(_contentContainerFrame);
CGFloat retweetContainerH;

if (isHasRetweetImage) {
retweetContainerH = CGRectGetMaxY(_retweetImageViewFrame) + padding;
} else {
retweetContainerH = CGRectGetMaxY(_retweetContentLabelFrame) + padding;
}

_retweetContainerFrame = CGRectMake(retweetContainerX, retweetContainerY, retweetContainerW, retweetContainerH);
} else {

//如果实体类数据没有这个subview显示的数据项
_retweetContainerFrame = CGRectZero;
}

//底部按钮容器
CGFloat bootmContainerX = 0;
CGFloat bootmContainerY;
CGFloat bootmContainerW = [UIScreen mainScreen].bounds.size.width;;
CGFloat bootmContainerH = 44;

if (isHasRetweet) {//有转发微博
bootmContainerY = CGRectGetMaxY(_retweetContainerFrame) + padding;
} else {//没有转发微博
bootmContainerY = CGRectGetMaxY(_contentContainerFrame) + padding;
}

_bottomContainerFrame = CGRectMake(bootmContainerX, bootmContainerY, bootmContainerW, bootmContainerH);

//最终Cell高度
_cellHeight = CGRectGetMaxY(_bottomContainerFrame) + padding;
}

@end
下面是Cell类

#import “StatusFrameModel.h”

/**

• 微博Cell
  */
  @interface WBTableViewCell : BaseTableViewCell

@end
@interface WBTableViewCell ()

//———————–原创微博———————–
@property (nonatomic, strong) UIView contentContainer;
@property (nonatomic, strong) UIImageView iconImageView;//头像
@property (nonatomic, strong) UIImageView vipImageView;//VIP图像
@property (nonatomic, strong) UIImageView photoImageView;//配图
@property (nonatomic, strong) UILabel nameLabel;//昵称
@property (nonatomic, strong) UILabel timeLabel;//时间
@property (nonatomic, strong) UILabel sourceLabel;//来源
@property (nonatomic, strong) UILabel contentLabel;//正文

//———————–转发微博———————–
@property (nonatomic, strong) UIView retweetContainer;
@property (nonatomic, strong) UILabel retweetContentLabel;
@property (nonatomic, strong) UIImageView *retweetImageView;

//———————–底部按钮———————–
@property (nonatomic, strong) UIView bottomContainer;
//@property (nonatomic, strong) UIView bottomContainer;
//@property (nonatomic, strong) UIView *bottomContainer;
@end
@implementation WBTableViewCell

• (NSString *)identifier {
  return NSStringFromClass([WBTableViewCell class]);
  }

• (instancetype)instanceWithTableView:(UITableView )tv {
  WBTableViewCell cell = [tv dequeueReusableCellWithIdentifier:[self identifier]];
  if (!cell) {
  cell = [[WBTableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:[self identifier]];
  }
  return cell;
  }

• (void)dealloc {

_iconImageView = nil;
_vipImageView = nil;
_photoImageView = nil;

_nameLabel = nil;
_timeLabel = nil;
_sourceLabel = nil;
_contentLabel = nil;
}

• (instancetype)initWithStyle:(UITableViewCellStyle)style
  reuseIdentifier:(NSString *)reuseIdentifier
  {
  self = [super initWithStyle:style reuseIdentifier:reuseIdentifier];
  if (self) {
  [self initSubviews];
  }
  return self;
  }

#pragma mark 添加所有subviews、以及设置

• (void)initSubviews {

//1. 让cell背景色透明，显示tableView的背景颜色
self.backgroundColor = [UIColor clearColor];

//2. 初始化原创微博subviews
[self initOriginWeiboSubviews];

//3. 初始化转发微博subviews
[self initRetweetWeiboSubviews];

//4. 底部按钮
[self initBottomWeiboSubviews];
}

• (void)initOriginWeiboSubviews {

//1. 初始化subviews
_contentContainer = [[UIView alloc] init];
_contentContainer.backgroundColor = [UIColor whiteColor];

_iconImageView = [[UIImageView alloc] init];
_vipImageView = [[UIImageView alloc] init];
_photoImageView = [[UIImageView alloc] init];

_nameLabel = [[UILabel alloc] init];
_timeLabel = [[UILabel alloc] init];
_contentLabel = [[UILabel alloc] init];
_sourceLabel = [[UILabel alloc] init];

//2. subview基础设置
_iconImageView.contentMode = UIViewContentModeCenter;
_vipImageView.contentMode = UIViewContentModeCenter;
_photoImageView.contentMode = UIViewContentModeCenter;

_nameLabel.font = NameFont;
_timeLabel.font = TimeFont;
_sourceLabel.font = TimeFont;

_contentLabel.font = ContentFont;
//自动换行Label
_contentLabel.numberOfLines = 0;
//最大显示宽大Label
_contentLabel.preferredMaxLayoutWidth = [UIScreen mainScreen].bounds.size.width - 2 * padding;

//3. 添加subviews

[_contentContainer addSubview:_iconImageView];
[_contentContainer addSubview:_vipImageView];
[_contentContainer addSubview:_photoImageView];
[_contentContainer addSubview:_nameLabel];
[_contentContainer addSubview:_timeLabel];
[_contentContainer addSubview:_contentLabel];
[_contentContainer addSubview:_sourceLabel];

[self.contentView addSubview:_contentContainer];
}

• (void)initRetweetWeiboSubviews {

_retweetContainer = [[UIView alloc] init];
_retweetContainer.backgroundColor = [UIColor orangeColor];
[self.contentView addSubview:_retweetContainer];

_retweetContentLabel = [[UILabel alloc] init];
_retweetContentLabel.font = ContentFont;
_retweetContentLabel.numberOfLines = 0;
_retweetContentLabel.preferredMaxLayoutWidth = [UIScreen mainScreen].bounds.size.width - 2 * padding;
[_retweetContainer addSubview:_retweetContentLabel];

_retweetImageView = [[UIImageView alloc] init];
[_retweetContainer addSubview:_retweetImageView];
}

• (void)initBottomWeiboSubviews {

_bottomContainer = [[UIView alloc] init];
[self.contentView addSubview:_bottomContainer];
_bottomContainer.backgroundColor = [UIColor blueColor];
}

#pragma mark 实体对象赋值协议方法实现

• (void)setupData:(id)data
  {
  //传入的是FrameModel
  if ([data isMemberOfClass:[StatusFrameModel class]])
  {

//1.转换成 FrameModel
StatusFrameModel frameModel = (StatusFrameModel )data;

//2. 完成subviews显示的实体对象数据
//如果对应数据项没有，就隐藏对应的subviews
[self setupSubviewsDatas:frameModel.status];

//3. 传入cell内部所有subviews显示的frame
//不显示的subview设置frame为CGRectZero
[self setupSubviewsFrame:frameModel];
}

}

/**

• 主要完成给subviews设置显示的数据，
• 全部subview都设置frame，不区分有没有数据
• 因为FrameModel中将没有数据项的subview的frame设置为CGRectZero，没有显示的大小
  */

• (void)setupSubviewsDatas:(Statuses *)status {

//1. 设置头像数据
[_iconImageView sd_setImageWithURL:[NSURL URLWithString:status.user.profile_image_url] placeholderImage:[UIImage imageNamed:@”avatar_default”] options:SDWebImageProgressiveDownload];

//3. 昵称显示
_nameLabel.text = status.user.name;

//4. 会员等级显示
if (status.user.isVip) {

_vipImageView.image = [UIImage imageNamed:@”common_icon_membership”];

//显示会员等级
_vipImageView.hidden = NO;

//修改名字颜色
_nameLabel.textColor = [UIColor orangeColor];

} else {

//隐藏会员等级
_vipImageView.hidden = YES;

//修改名字颜色
_nameLabel.textColor = [UIColor blackColor];
}

//5. 配图
_photoImageView.backgroundColor = [UIColor redColor];

if (status.pic_urls.count > 0)
{
_photoImageView.hidden = NO;

} else {

_photoImageView.hidden = YES;
}

//6. 时间
_timeLabel.text = status.created_at;

//7.正文
_contentLabel.text = status.text;

//8. 来源
_sourceLabel.text = status.source;
_sourceLabel.textColor = [UIColor lightGrayColor];

//9. 转发微博
if (status.retweeted_status) {//有转发微博

//9.1 转发微博容器
_retweetContainer.hidden = NO;

//9.2 转发内容
_retweetContentLabel.text = [status retweetContent];

//9.3 转发配图
if (status.retweeted_status.pic_urls) {//转发微博有配图
_retweetImageView.hidden = NO;
_retweetImageView.backgroundColor = [UIColor yellowColor];

} else {//转发微博无配图
_retweetImageView.hidden = YES;
}

} else {//无转发微博
_retweetContainer.hidden = YES;
}
}

/**

• 主要完成给subview设置显示的frame
  */

• (void)setupSubviewsFrame:(StatusFrameModel *)frameModel
  {

//1.
_contentContainer.frame = frameModel.contentContainerFrame;

//2.
_iconImageView.frame = frameModel.iconImageViewFrame;

//3.
_nameLabel.frame = frameModel.nameLabelFrame;

//4.
_vipImageView.frame = frameModel.vipImageViewFrame;

//5.
_photoImageView.frame = frameModel.photoImageViewFrame;

//6.
_timeLabel.frame = frameModel.timeLabelFrame;

//7.
_contentLabel.frame = frameModel.contentLabelFrame;

//8.
_sourceLabel.frame = frameModel.sourceLabelFrame;

//9.
_retweetContainer.frame = frameModel.retweetContainerFrame;
_retweetContentLabel.frame = frameModel.retweetContentLabelFrame;
_retweetImageView.frame = frameModel.retweetImageViewFrame;

//10.
_bottomContainer.frame = frameModel.bottomContainerFrame;
}

@end
cell不用每次对传入的实体对象再自己重新计算frame了，直接使用外部传入的FraneModel对象保存的所有的subviews对应的frame.

有一个开源的Cell高度缓存框架，有时间去看看…

使用AutoLayout形式的cell高度计算

首先定义一个用于计算Cell内部约束得到最后高度的协议， ZSYAutoLayoutCellProtocol.h

#import <Foundation/Foundation.h>

@protocol ZSYAutoLayoutCellProtocol;

static CGFloat ZSYDynamicTableViewCellAccessoryWidth = 33;

static NSMutableArray *cellArray;

typedef id (^setupCellBlock)(id cellToSetup);

@protocol ZSYAutoLayoutCellProtocol

• (void)setupDataItem:(id)data;

• (CGSize)sizeForCellWithDefaultSize:(CGSize)defaultSize setupCellBlock:(setupCellBlock)block;

@end
然后BaseCell实现上面的协议方法，用于计算约束最后的cell高度

#import <UIKit/UIKit.h>

@interface BaseCell : UITableViewCell

/**

• 传入TableView查询一个cell对象，该identifier由各自Cell类自己管理，不向外暴露
  */

• (instancetype)dequeFromTableView:(UITableView *)tableView;

/**

• 传入实体类对象，设置subviews的数据显示
  */

• (void)setupData:(id)data;

/**

• 初始化subviews
  */

• (void)setupSubviews;

@end

#import “BaseCell.h”

@implementation BaseCell

//子类实现

• (instancetype)dequeFromTableView:(UITableView *)tableView {return nil;}

//子类实现

• (void)setupData:(id)data {}

//子类实现

• (void)setupSubviews {}

• (instancetype)initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(NSString *)reuseIdentifier {
  if (self = [super initWithStyle:style reuseIdentifier:reuseIdentifier]) {
  [self setupSubviews];
  }
  return self;
  }

//根据Cell内部设置的约束，计算得到cell的总高度

• (CGSize)sizeForCellWithDefaultSize:(CGSize)defaultSize setupCellBlock:(setupCellBlock)block {
  __block ZSYBaseCell *cell = nil;

//使用一个static数组，给每一类型的Cell保存一个对象，用来计算高度的
[cellArray enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL stop) {
if ([obj isKindOfClass:[[self class] class]]) {
cell = obj; stop = YES;
}
}];

//如果数组还不存在，就创建一个cell，并保存到数组中，以后直接使用，不会再创建
if (!cell) {
cell = [[[self class] alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:@”XZHAutoLayoutCellIdentifier”];
cell.frame = CGRectMake(0, 0, defaultSize.width, defaultSize.height);
[cellArray addObject:cell];
}

//回传用于计算约束的cell对象，返回给TableView，让TableView给这个回传的cell对象填充所有的显示数据
cell = block((id) cell);

//通知系统重新计算frame或约束
[cell setNeedsLayout];
[cell setNeedsUpdateConstraints];
[cell layoutIfNeeded];

//通过苹果提供的api直接计算约束，得到cell的高度
//注意，必须保证cell内部的所有subviews的约束设置正确
CGSize size = [cell.contentView systemLayoutSizeFittingSize:UILayoutFittingCompressedSize];
size.height += 1.0f;

return size;
}

@end
如上可以看到，设置实体对象的数据之后，需要通知系统重新计算约束

[cell setNeedsLayout];
[cell setNeedsUpdateConstraints];
[cell layoutIfNeeded];
所以，每一次数据改变，需要重新计算一遍cell内部所有约束对应的frame，相比前面直接使用FrameModel可能性能稍微差一点，但是还是简单多了。所以如果对性能要求不高，要求简单的还是使用AutoLayout吧.

Cell之间做一些间隙

第一步，设置TableView的backgroudColor 或 backgroudView

第二步、重写自定义cell的setFrame:方法，缩小cell的frame

• (void)setFrame:(CGRect)frame {

//1. 对frame做出修改
frame.x += 10;
frame.w -= 10 * 2;

//2. 再将修改的frame交给父类执行
[super setFrame:frame]
}