- ViewReusePool 类 (通过队列实现重用机制)
#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>
/*
实现重用机制的类
*/
@interface ViewReusePool : NSObject
// 从重用池中取出一个可重用的view
-(UIView *)dequeueReusableView;
// 向重用池当中添加一个视图
-(void)addUsingView:(UIView *)view;
// 重置 将当前使用的视图放到可重用队列中
-(void)reset;
@end
#import "ViewReusePool.h"
@interface ViewReusePool ()
@property(nonatomic,strong)NSMutableSet *waitUsedQueue;// 等待使用的队列
@property(nonatomic,strong)NSMutableSet *usingQueue; // 使用中的队列
@end
@implementation ViewReusePool
-(instancetype)init
{
self = [super init];
if (self) {
_waitUsedQueue = [[NSMutableSet alloc] init];
_usingQueue = [[NSMutableSet alloc] init];
}
return self;
}
-(UIView *)dequeueReusableView
{
UIView *view = [_waitUsedQueue anyObject]; // 等待队列中返回任意一个view
if (view == nil) {
return nil;
}
// 队列移动
[_waitUsedQueue removeObject:view];
[_usingQueue addObject:view];
return view;
}
- (void)addUsingView:(UIView *)view
{
if (view == nil) {
return;
}
// 将视图添加到使用的队列中
[_usingQueue addObject:view];
}
-(void)reset
{
UIView *view = nil;
while ((view = [_usingQueue anyObject])) {
NSLog(@"view - %@",view);
// 从使用队列中移除
[_usingQueue removeObject:view];
// 加入等待队列中
[_waitUsedQueue addObject:view];
}
}
@end
- IndexTableView 类(继承于uitableview,实现索引按钮的重用功能)
#import <UIKit/UIKit.h>
@protocol IndexTableViewDataSource <NSObject>
// 获取tableview的字母索引数据的方法
-(NSArray *)indexTitlesForIndexTableView:(UITableView *)tableView;
@end
@interface IndexTableView : UITableView
@property(nonatomic,weak)id<IndexTableViewDataSource> indexDataSource;
@end
#import "IndexTableView.h"
#import "ViewReusePool.h"
@interface IndexTableView ()
@property(nonatomic,strong)UIView *containerView;
@property(nonatomic,strong)ViewReusePool *reusePool;
@end
@implementation IndexTableView
-(void)reloadData
{
[super reloadData];
if (_containerView == nil) {
_containerView = [[UIView alloc] initWithFrame:CGRectZero];
_containerView.backgroundColor = [UIColor whiteColor];
// 避免索引条随着table滚动
[self.superview insertSubview:_containerView aboveSubview:self];
}
if (_reusePool == nil) {
_reusePool = [[ViewReusePool alloc] init];
}
// 标记所有视图为可重用状态
[_reusePool reset];
[self reloadIndexedBar];
}
-(void)reloadIndexedBar
{
NSArray *arrayTitles = nil;
if ([self.indexDataSource respondsToSelector:@selector(indexTitlesForIndexTableView:)]) {
arrayTitles = [self.indexDataSource indexTitlesForIndexTableView:self];
}
// 判断字母索引是否为空
if (!arrayTitles || arrayTitles.count <= 0) {
[_containerView setHidden:YES];
return;
}
NSUInteger count = arrayTitles.count;
CGFloat buttonWidth = 60.0f;
CGFloat buttonHeight = self.frame.size.height / count;
for (NSInteger i = 0; i < arrayTitles.count; i++) {
NSString *title = [arrayTitles objectAtIndex:i];
// 从重用池取出一个button来
UIButton *button = (UIButton *)[_reusePool dequeueReusableView];
if (button == nil) {
button = [[UIButton alloc] initWithFrame:CGRectZero];
button.backgroundColor = [UIColor whiteColor];
[_reusePool addUsingView:button];
NSLog(@"创建一个button");
} else {
NSLog(@"button重用了");
}
[_containerView addSubview:button];
[button setTitle:title forState:UIControlStateNormal];
[button setTitleColor:[UIColor blueColor] forState:UIControlStateNormal];
button.frame = CGRectMake(0, i * buttonHeight, buttonWidth, buttonHeight);
}
[_containerView setHidden:NO];
_containerView.frame = CGRectMake(self.frame.origin.x + self.frame.size.width - buttonWidth, self.frame.origin.y, buttonWidth, self.frame.size.height);
}
@interface ViewController ()<UITableViewDataSource,UITableViewDelegate,IndexTableViewDataSource>
@property(nonatomic,strong)IndexTableView *tableView;
@property(nonatomic,strong)UIButton *button;
@property(nonatomic,copy)NSMutableArray *dataSource;
@end
- (void)viewDidLoad {
[super viewDidLoad];
// 创建一个tableview
_tableView = [[IndexTableView alloc] initWithFrame:CGRectMake(0.0f, 60.0f, self.view.frame.size.width, self.view.frame.size.height - 60.0f) style:UITableViewStylePlain];
_tableView.delegate = self;
_tableView.dataSource = self;
_tableView.indexDataSource = self;
[self.view addSubview:_tableView];
// 创建一个按钮
_button = [UIButton buttonWithType:UIButtonTypeCustom];
_button.frame = CGRectMake(0.0f, 20.0f, self.view.frame.size.width, 40.0f);
_button.backgroundColor = [UIColor redColor];
[_button setTitle:@"reload" forState:UIControlStateNormal];
[_button addTarget:self action:@selector(reloadAction) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:_button];
// 数据
_dataSource = [[NSMutableArray alloc] init];
for (NSInteger i = 0; i < 100; i++) {
[_dataSource addObject:@(i+1)];
}
}
#pragma mark - UITableViewDataSource
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
return _dataSource.count;
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *identifier = @"reused";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:identifier];
if (cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:identifier];
}
cell.textLabel.text = [[_dataSource objectAtIndex:indexPath.row] stringValue];
return cell;
}
#pragma mark - UITableViewDelegate
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
return 40.0f;
}
#pragma mark - IndexTableViewDataSource
-(NSArray *)indexTitlesForIndexTableView:(UITableView *)tableView
{
// 奇数次调用返回6个字母 偶数次返回11个
static BOOL change = NO;
if (change) {
change = NO;
return @[@"A",@"B",@"C",@"E",@"F",@"G",@"H",@"I",@"J",@"K"];
} else {
change = YES;
return @[@"A",@"B",@"C",@"D",@"E",@"F"];
}
}
#pragma mark - action method
-(void)reloadAction
{
NSLog(@"reloadAction");
[_tableView reloadData];
}
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