#import <Foundation/Foundation.h>@interface LLFriend : NSObject/** *  icon */@property (nonatomic, copy) NSString *icon;/** *  intro */@property (nonatomic, copy) NSString *intro;/** *  name */@property (nonatomic, copy) NSString *name;/** *  vip */@property (nonatomic, assign, getter=isVip) BOOL vip;- (instancetype)initWithDic:(NSDictionary *)dic;+ (instancetype)friendWithDic:(NSDictionary *)dic;@end

#import "LLFriend.h"@implementation LLFriend- (instancetype)initWithDic:(NSDictionary *)dic{    if (self = [super init]) {        [self setValuesForKeysWithDictionary:dic];    }    return self;}+ (instancetype)friendWithDic:(NSDictionary *)dic{    return [[self alloc] initWithDic:dic];}@end

#import <Foundation/Foundation.h>@interface LLFriendGroup : NSObject/** *  friends模型 */@property (nonatomic, strong) NSArray *friends;/** *  name */@property (nonatomic, copy) NSString *name;/** *  online */@property (nonatomic, assign) int  online;/** *  是否合闭 */@property (nonatomic, assign, getter=isOpened) BOOL opened;- (instancetype)initWithDic:(NSDictionary *)dic;+ (instancetype)friendGroupWithDic:(NSDictionary *)dic;+ (NSArray *)friendGroupList;@end

#import "LLFriendGroup.h"#import "LLFriend.h"@implementation LLFriendGroup- (instancetype)initWithDic:(NSDictionary *)dic{    if (self = [super init]) {        [self setValuesForKeysWithDictionary:dic];                NSMutableArray *tmpArray = [[NSMutableArray alloc] initWithCapacity:self.friends.count];        for (NSDictionary *dic in self.friends) {                        LLFriend *friend = [LLFriend friendWithDic:dic];            [tmpArray addObject:friend];        }        self.friends = tmpArray;    }    return self;}+ (instancetype)friendGroupWithDic:(NSDictionary *)dic{    return [[self alloc] initWithDic:dic];}+ (NSArray *)friendGroupList{    NSString *path = [[NSBundle mainBundle] pathForResource:@"friends" ofType:@"plist"];    NSArray *dicArr = [NSArray arrayWithContentsOfFile:path];        NSMutableArray *tmpArr = [[NSMutableArray alloc] initWithCapacity:dicArr.count];    for (NSDictionary *dic in dicArr) {                LLFriendGroup *friendGroup = [LLFriendGroup friendGroupWithDic:dic];                [tmpArr addObject:friendGroup];    }    return tmpArr;}@end

#import <UIKit/UIKit.h>@class LLFriendGroup;@class LLHeaderView;@protocol LLFriendGroupDelegate <NSObject>@optional- (void)friendGroupDidClickNameView:(LLHeaderView *)friendGroup;@end@interface LLHeaderView : UITableViewHeaderFooterView@property (nonatomic, weak) id<LLFriendGroupDelegate> delegate;@property (nonatomic, strong) LLFriendGroup *group;+ (instancetype)headerViewWith:(UITableView *)tableView;@end

#import "LLHeaderView.h"#import "LLFriendGroup.h"@interface LLHeaderView ()@property (nonatomic, weak) UIButton *nameView;@property (nonatomic, weak) UILabel *onlineView;@end@implementation LLHeaderView+ (instancetype)headerViewWith:(UITableView *)tableView{    static NSString *ID = @"headerView";    LLHeaderView *headerView = [tableView dequeueReusableHeaderFooterViewWithIdentifier:ID];    if (!headerView) {                headerView = [[LLHeaderView alloc] initWithReuseIdentifier:ID];    }        return headerView;}- (instancetype)initWithReuseIdentifier:(NSString *)reuseIdentifier{    if (self = [super initWithReuseIdentifier:reuseIdentifier]) {               // 按钮        UIButton *nameView = [UIButton buttonWithType:UIButtonTypeCustom];        [self.contentView addSubview:nameView];        self.nameView = nameView;        [nameView setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];        nameView.titleLabel.font = [UIFont systemFontOfSize:16];        [nameView setImage:[UIImage imageNamed:@"buddy_header_arrow"] forState:UIControlStateNormal];        [self.nameView setBackgroundImage:[UIImage imageNamed:@"buddy_header_bg"] forState:UIControlStateNormal];        [self.nameView setBackgroundImage:[UIImage imageNamed:@"buddy_header_bg_highlighted"]  forState:UIControlStateHighlighted];                // 设置按钮中内容        nameView.contentHorizontalAlignment = UIControlContentHorizontalAlignmentLeft;        nameView.contentEdgeInsets = UIEdgeInsetsMake(0, 10, 0, 0);        nameView.titleEdgeInsets = UIEdgeInsetsMake(0, 10, 0, 0);                // 设置按钮图片旋转变形的状态#warning 设置按钮图片旋转变形的状态        nameView.imageView.contentMode = UIViewContentModeCenter;        nameView.imageView.clipsToBounds = NO;                // 按钮注册事件        [self.nameView addTarget:self action:@selector(clickNameView:) forControlEvents:UIControlEventTouchUpInside];                // label        UILabel  *onlineView = [[UILabel alloc] init];        [self.contentView addSubview:onlineView];         self.onlineView = onlineView;                onlineView.textAlignment = NSTextAlignmentRight;        onlineView.font = [UIFont systemFontOfSize:14];        onlineView.textColor = [UIColor grayColor];    }    return self;}- (void)clickNameView:(UIButton *)sender{    self.group.opened = !self.group.isOpened;    if (self.group.isOpened) {        sender.imageView.transform = CGAffineTransformMakeRotation(M_PI_2);    } else {        sender.imageView.transform = CGAffineTransformMakeRotation(0);    }        if ([self.delegate respondsToSelector:@selector(friendGroupDidClickNameView:)]) {                [self.delegate friendGroupDidClickNameView:self];    }}// 布局子控件- (void)layoutSubviews{#warning 必须调用父类的方法，否则按钮不能点击    [super layoutSubviews];        self.nameView.frame = self.bounds;    CGFloat onlineY = 0;    CGFloat onlineW = 150;    CGFloat onlineH = self.bounds.size.height;    CGFloat onlineX = self.bounds.size.width - onlineW - 10;    self.onlineView.frame = CGRectMake(onlineX, onlineY, onlineW, onlineH);}- (void)setGroup:(LLFriendGroup *)group{    _group = group;    [self.nameView setTitle:group.name forState:UIControlStateNormal];    self.onlineView.text = [NSString stringWithFormat:@"%d/%ld",group.online, group.friends.count];        // set方法中一定要给子控件重新都赋值，否则可能因为cell重用引起的问题    if (self.group.isOpened) {        self.nameView.imageView.transform = CGAffineTransformMakeRotation(M_PI_2);            } else {                self.nameView.imageView.transform = CGAffineTransformMakeRotation(0);            }}@end

#import <UIKit/UIKit.h>@class LLFriend;@interface LLFriendCell : UITableViewCell@property (nonatomic, strong) LLFriend *friendData;+ (instancetype)friendCellWith:(UITableView *)tableView;@end

#import "LLFriendCell.h"#import "LLFriend.h"@implementation LLFriendCell+ (instancetype)friendCellWith:(UITableView *)tableView{    static NSString *ID = @"friendCell";    LLFriendCell *cell = [tableView dequeueReusableCellWithIdentifier:ID];    if (!cell) {                cell = [[LLFriendCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:ID];    }    return cell;}- (void)setFriendData:(LLFriend *)friendData{    _friendData = friendData;        self.imageView.image = [UIImage imageNamed:friendData.icon];    self.textLabel.text = friendData.name;    self.detailTextLabel.text = friendData.intro;        if (friendData.isVip) {                self.textLabel.textColor = [UIColor redColor];    } else {                self.textLabel.textColor = [UIColor blackColor];    }}@end

#import "ViewController.h"#import "LLFriend.h"#import "LLFriendGroup.h"#import "LLHeaderView.h"#import "LLFriendCell.h"@interface ViewController ()<LLFriendGroupDelegate>@property (nonatomic, strong) NSArray *friendGroups;@end@implementation ViewController- (void)viewDidLoad {    [super viewDidLoad];    // Do any additional setup after loading the view, typically from a nib.    self.tableView.sectionHeaderHeight = 44;}#pragma mark - 懒加载数据- (NSArray *)friendGroups{    if (!_friendGroups) {                _friendGroups = [LLFriendGroup friendGroupList];    }    return _friendGroups;}#pragma mark - 数据源方法- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView{    return self.friendGroups.count;}- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{    LLFriendGroup *group = self.friendGroups[section];    return group.isOpened ? group.friends.count : 0;//    return 0;}- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{    LLFriendCell *cell = [LLFriendCell friendCellWith:tableView];    cell.friendData = [self.friendGroups[indexPath.section] friends][indexPath.row];    return cell;}#pragma mark - tableView的代理方法- (UIView *)tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section{    LLHeaderView *headerView = [LLHeaderView headerViewWith:tableView];    headerView.group = self.friendGroups[section];    headerView.delegate = self;    return headerView;}#pragma mark - LLFriendGroup代理方法- (void)friendGroupDidClickNameView:(LLHeaderView *)friendGroup{//    NSIndexSet *indexSet = [NSIndexSet indexSetWithIndex:<#(NSUInteger)#>]//    self.tableView reloadSections:<#(NSIndexSet *)#> withRowAnimation:<#(UITableViewRowAnimation)#>    [self.tableView reloadData];}- (BOOL)prefersStatusBarHidden{    return YES;}@end

4，按钮上的图片旋转后被拉伸的处理

     设置按钮内部的imageView的内容模式为居中，因为默认会填充整个imageView

     btn.imageView.contentMode = UIViewContentModeCenter

     btn.imageView.clipsToBounds = NO; 默认为yes表示超出的部分减掉

5：

 

- (instancetype)initWithReuseIdentifier:(NSString *)reuseIdentifier

{

    if (self = [super initWithReuseIdentifier:reuseIdentifier]) {

        NSLog(@"%f", self.frame.size.height); // height为0；

}  

init方法中，self对象和它父类的frame初始化过程中都为0；

所以没法确定子类的frame，在layoutSubview方法中父类的frame已经确定了