仿QQ聊天界面<一>

先上图：

首先需要两个模型：

1－>数据模型

2－>位置模型

数据模型代码如下：

Message.h文件里：
#import <Foundation/Foundation.h>
typedef enum {
    MessagesTypeMe  =  0  ,    //自己发的
    MessagesTypeOther          //别人发的
}MessagesType;
@interface Messages : NSObject
/**
 *  聊天内容
 */
@property (nonatomic ,copy)NSString *text;
/**
 *  发送时间
 */
@property (nonatomic ,copy)NSString *time;
/**
 * 消息类型
 */
@property (nonatomic ,assign)MessagesType *type;
+ (instancetype)messageWithDict:(NSDictionary *)dict;
- (instancetype)initWithDict:(NSDictionary *)dict;
@end

Messages.m文件里
#import "Messages.h"
@implementation Messages
+ (instancetype)messageWithDict:(NSDictionary *)dict
{
    return [[self alloc] initWithDict:dict];
}

- (instancetype)initWithDict:(NSDictionary *)dict
{
    if (self = [super init]) {
    ／／用KVC字典转模型
        [self setValuesForKeysWithDictionary:dict];
    }
    return self;
}

位置模型代码如下：

MJMessageFrame.h文件里面

// 正文的字体
#define MJTextFont [UIFont systemFontOfSize:15]

#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>

@class MJMessage;

@interface MJMessageFrame : NSObject
/**
 *  头像的frame
 */
@property (nonatomic, assign, readonly) CGRect iconF;
/**
 *  时间的frame
 */
@property (nonatomic, assign, readonly) CGRect timeF;
/**
 *  正文的frame
 */
@property (nonatomic, assign, readonly) CGRect textF;
/**
 *  cell的高度
 */
@property (nonatomic, assign, readonly) CGFloat cellHeight;

/**
 *  数据模型
 */
@property (nonatomic, strong) MJMessage *message;
@end

#import "MJMessageFrame.h"
#import "MJMessage.h"

@implementation MJMessageFrame
/**
 *  计算文字尺寸
 *
 *  @param text    需要计算尺寸的文字
 *  @param font    文字的字体
 *  @param maxSize 文字的最大尺寸
 */
- (CGSize)sizeWithText:(NSString *)text font:(UIFont *)font maxSize:(CGSize)maxSize
{
    NSDictionary *attrs = @{NSFontAttributeName : font};
    return [text boundingRectWithSize:maxSize options:NSStringDrawingUsesLineFragmentOrigin attributes:attrs context:nil].size;
}

- (void)setMessage:(MJMessage *)message
{
    _message = message;
    // 间距
    CGFloat padding = 10;
    // 屏幕的宽度
    CGFloat screenW = [UIScreen mainScreen].bounds.size.width;

    // 1.时间
    CGFloat timeX = 0;
    CGFloat timeY = 0;
    CGFloat timeW = screenW;
    CGFloat timeH = 40;
    _timeF = CGRectMake(timeX, timeY, timeW, timeH);

    // 2.头像
    CGFloat iconY = CGRectGetMaxY(_timeF);
    CGFloat iconW = 40;
    CGFloat iconH = 40;
    CGFloat iconX;
    if (message.type == MJMessageTypeOther) {// 别人发的
        iconX = padding;
    } else { // 自己的发的
        iconX = screenW - padding - iconW;
    }
    _iconF = CGRectMake(iconX, iconY, iconW, iconH);

    // 3.正文
    CGFloat textY = iconY;
    // 文字的尺寸
    CGSize textMaxSize = CGSizeMake(150, MAXFLOAT);
    CGSize textSize = [self sizeWithText:message.text font:MJTextFont maxSize:textMaxSize];
    CGFloat textX;
    if (message.type == MJMessageTypeOther) {// 别人发的
        textX = CGRectGetMaxX(_iconF) + padding;
    } else {// 自己的发的
        textX = iconX - padding - textSize.width;
    }
//    _textF = CGRectMake(textX, textY, textSize.width, textSize.height);
    _textF = (CGRect){{textX, textY}, textSize};

    // 4.cell的高度
    CGFloat textMaxY = CGRectGetMaxY(_textF);
    CGFloat iconMaxY = CGRectGetMaxY(_iconF);
    _cellHeight = MAX(textMaxY, iconMaxY) + padding;
}

@end

自定义一个cell继承于UITableViewCell的.h文件里面

#import <UIKit/UIKit.h>

@class MJMessageFrame;

@interface MJMessageCell : UITableViewCell

+ (instancetype)cellWithTableView:(UITableView *)tableView;

@property (nonatomic, strong) MJMessageFrame *messageFrame;
@end

MJMessageCell.m里面
#import "MJMessageCell.h"
#import "MJMessageFrame.h"
#import "MJMessage.h"

@interface MJMessageCell()
/**
 *  时间
 */
@property (nonatomic, weak) UILabel *timeView;
/**
 *  头像
 */
@property (nonatomic, weak) UIImageView *iconView;
/**
 *  正文
 */
@property (nonatomic, weak) UIButton *textView;
@end

@implementation MJMessageCell
+ (instancetype)cellWithTableView:(UITableView *)tableView
{
    static NSString *ID = @"message";
    MJMessageCell *cell = [tableView dequeueReusableCellWithIdentifier:ID];
    if (cell == nil) {
        cell = [[MJMessageCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:ID];
    }
    return cell;
}

- (id)initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(NSString *)reuseIdentifier
{
    self = [super initWithStyle:style reuseIdentifier:reuseIdentifier];
    if (self) {
        // 子控件的创建和初始化
        // 1.时间
        UILabel *timeView = [[UILabel alloc] init];
//        timeView.backgroundColor = [UIColor redColor];
        timeView.textAlignment = NSTextAlignmentCenter;
        timeView.textColor = [UIColor grayColor];
        timeView.font = [UIFont systemFontOfSize:13];
        [self.contentView addSubview:timeView];
        self.timeView = timeView;

        // 2.头像
        UIImageView *iconView = [[UIImageView alloc] init];
        [self.contentView addSubview:iconView];
        self.iconView = iconView;

        // 3.正文
        UIButton *textView = [[UIButton alloc] init];
        textView.titleLabel.numberOfLines = 0; // 自动换行
        textView.backgroundColor = [UIColor purpleColor];
        textView.titleLabel.font = MJTextFont;
        [self.contentView addSubview:textView];
        self.textView = textView;

        // 4.设置cell的背景色
        self.backgroundColor = [UIColor clearColor];
    }
    return self;
}

- (void)setMessageFrame:(MJMessageFrame *)messageFrame
{
    _messageFrame = messageFrame;

    MJMessage *message = messageFrame.message;

    // 1.时间
    self.timeView.text = message.time;
    self.timeView.frame = messageFrame.timeF;

    // 2.头像
    NSString *icon = (message.type == MJMessageTypeMe) ? @"me" : @"other";
    self.iconView.image = [UIImage imageNamed:icon];
    self.iconView.frame = messageFrame.iconF;

    // 3.正文
    [self.textView setTitle:message.text forState:UIControlStateNormal];
    self.textView.frame = messageFrame.textF;
}

@end

最后在需要聊天界面的控制器里

#import "ViewController.h"
#import "MJMessage.h"
#import "MJMessageFrame.h"
#import "MJMessageCell.h"

@interface ViewController ()<UITableViewDataSource, UITableViewDelegate>
@property (nonatomic ,strong)NSMutableArray *messagesFrames;

@end

@implementation ViewController

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

-(NSMutableArray*)messagesFrames{

    if (_messagesFrames == nil) {
        NSArray *dictArray = [NSArray arrayWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"messages.plist" ofType:nil]];

        NSMutableArray *mfArray  = [NSMutableArray array];
        for (NSDictionary *dict  in dictArray) {

            //初始化一个消息模型
            MJMessage *msg = [MJMessage messageWithDict:dict];

            //frame模型
            MJMessageFrame *mf = [[MJMessageFrame alloc]init];

            mf.message = msg;

            //添加模型
            [mfArray addObject:mf];

        }

        _messagesFrames = mfArray;

    }
    return  _messagesFrames;

}

-(NSInteger )tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{
   return   self.messagesFrames.count;
}

-(UITableViewCell *) tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{

    // 1.创建cell
    MJMessageCell *cell = [MJMessageCell cellWithTableView:tableView];

    // 2.给cell传递模型
    cell.messageFrame = self.messagesFrames[indexPath.row];

    // 3.返回cell
    return cell;
}

-(CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath{
    MJMessageFrame *ljfmf = self.messagesFrames[indexPath.row];

    return ljfmf.cellHeight;

}

.