QQ好友列表很炫？其实很简单！

相信地球人都用QQ的,我们每天都会打开QQ,但是你去注意到他是怎么实现的吗？

话不多说先上图：

该数据都是用plist文件存储

接下来带你看下plist文件分析下数据结构

图一：

每一组都是一个组模型，一组相当于一个好友分组。

图二

每组里面都有一个friends数组存放该组的好友数

@interface JFFriend : NSObject
/**
 *  头像
 */
@property (nonatomic ,copy)NSString *icon;
/**
 *  个性签名
 */
@property (nonatomic ,copy)NSString *intro;
/**
 *  名字
 */
@property (nonatomic ,copy)NSString *name;
/**
 *  getter这样写的好处是控制get方法在需要的时候非常顺
 *  苹果官方建议这样写：规范
 */
@property (nonatomic , assign , getter=isvip) BOOL vip;

+(instancetype)friendWithDict:(NSDictionary *)dict;
-(instancetype)initWithDict:(NSDictionary *)dict;

+(instancetype)friendWithDict:(NSDictionary *)dict{

       return  [[self alloc]initWithDict:dict];
}

-(instancetype)initWithDict:(NSDictionary *)dict{
    if (self = [super init]) {
        [self setValuesForKeysWithDictionary:dict];
    }
    return self;
}

#import <UIKit/UIKit.h>
@class JFFriendGroup, JFHeaderView;

/**
 *  定义代理一般以控件名字家delegate,这是规范
 */
@protocol JFHeaderViewDelegate <NSObject>
@optional
-(void)headerViewDidClick:(JFHeaderView*)view;

@end

@interface JFHeaderView : UITableViewHeaderFooterView

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

@property(nonatomic, strong)JFFriendGroup *group;
/**
 *  这里用id类型是返回任意类型,不依赖任何一个类
 *  也就是在任何一个类里面都可以使用
 */
@property (nonatomic, weak)id<JFHeaderViewDelegate>delegate;

#import "JFHeaderView.h"
#import "JFFriendGroup.h"
#define WIDTH  (self.frame.size.width)
#define HEIGHT  (self.frame.size.height)

@interface JFHeaderView ()
@property(nonatomic, weak)UILabel *countView;
@property(nonatomic, weak)UIButton *nameView;

@end
@implementation JFHeaderView

+(instancetype)headerViewWithTableView:(UITableView * )tableView{
    static NSString *headId = @"headId";
    JFHeaderView *headerView = [tableView dequeueReusableHeaderFooterViewWithIdentifier:headId];
    if (headerView == nil) {
        headerView = [[JFHeaderView alloc]initWithReuseIdentifier:headId];
    }
    return headerView;

}

/**
 *  在这个初始化方法中,JFHeaderView的frame\bounds没有值
 */
-(id)initWithReuseIdentifier:(NSString *)reuseIdentifier{
    if (self = [super init]) {
        //添加子控件
        //1.添加按钮
        UIButton *nameView = [UIButton buttonWithType:UIButtonTypeCustom];
        [nameView setBackgroundImage:[UIImage imageNamed:@"buddy_header_bg"] forState:UIControlStateNormal];
        [nameView setBackgroundImage:[UIImage imageNamed:@"buddy_header_bg_highlighted"] forState:UIControlStateHighlighted];
        //设置箭头
        [nameView setImage:[UIImage imageNamed:@"buddy_header_arrow"] forState:UIControlStateNormal];
        [nameView setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
        //内容左对齐
        nameView.contentHorizontalAlignment = UIControlContentHorizontalAlignmentLeft;
        //设置按钮的内边距
        nameView.titleEdgeInsets = UIEdgeInsetsMake(0, 10, 0, 0);
        nameView.contentEdgeInsets = UIEdgeInsetsMake(0, 10, 0, 0);
        [nameView addTarget:self action:@selector(nameViewClick) forControlEvents:UIControlEventTouchUpInside];
        [self.contentView addSubview:nameView];
        self.nameView = nameView;
        //2.添加好友数
        UILabel *countView = [[UILabel alloc]init];
        countView.textAlignment = NSTextAlignmentRight;
        countView.textColor = [UIColor grayColor];
        [self.contentView addSubview:countView];
        self.countView =  countView;
    }
    return  self;

}
/**
 *  当一个控件的frame发生改变时就会调用
 *  一般在这里布局内部的子控件（设置子控件的freme）
 */
-(void)layoutSubviews{

    //注：这个地方一定要调用父类的方法
    [super layoutSubviews];

    //1.设置按钮的freme
    self.nameView.frame = self.bounds;
    //2.设置好友数的frame
    CGFloat countY = 0;
    CGFloat countH =  HEIGHT;
    CGFloat countW = 150;
    CGFloat countX = WIDTH - 10 - countW;
    self.countView.frame = CGRectMake(countX, countY, countW, countH);

}

-(void)setGroup:(JFFriendGroup *)group{
    _group = group;
    //1.设置组名
    [self.nameView setTitle:group.name forState:UIControlStateNormal];
    //2.设置好友数（在线数/总数）
    self.countView.text = [NSString stringWithFormat:@"%d/%lu",group.online,(unsigned long)group.friends.count];;

}

-(void)nameViewClick{
    //1.修改模型标记(状态取反)
    self.group.opened = !self.group.isOpened;
    if ([self.delegate respondsToSelector:@selector(headerViewDidClick:)]) {
        [self.delegate headerViewDidClick:self];
    }

}
/**
 *  但一个控件被添加到控件的时候会调用
 */
-(void)didMoveToSuperview{
    if (self.group.opened) {
        self.nameView.imageView.transform = CGAffineTransformMakeRotation(M_PI_2);
    }else{
        self.nameView.imageView.transform = CGAffineTransformMakeRotation(0);

    }
}

以上是部分代码，有问题的可以关注我然后提出来我们一起探讨

祝好：2015 － 08 － 09 22 － 53。

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