iOS开发--自定义列表控件

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   这两天项目比较闲，在空余之际，尝试自己实现列表控件。从动工到初步完成大概花了一天时间，目前实现了列表的简单功能，后续将考虑加入cell重用机制、惯性特征以及删除cell等功能。项目代码已经放到了github上，地址：https://github.com/wanglichun/CustomTableView。

   在实现之前，需要了解列表控件的运行原理，我之前的一篇博客《列表控件实现原理解析》中有介绍。去年由于项目需要，使用lua语言自定义过双重列表（大列表嵌套小列表），这次改用objc实现，实现的思路和以前相同，只是换了个语言，因此速度比较快。下面分步骤介绍实现过程。

    总体目录结构：

    目录结构说明：

1、TablewView目录：CSTableView（CustomTableView的缩写）为自定义的列表控件，CSTableViewCell为列表的单元格；

2、RootViewController中包含了一个CSTableView的测试例子。

步骤一：列表单元格CSTableViewCell实现

    为了节省时间，我采用xib的方式构建了cell，并且cell中只包含了标题信息，用户如果想实现复杂的cell，可以继承CSTableViewCell扩展cell。需要注意的是，cell这一层并不处理触摸事件，而是传递给父控件CSTableView处理。

代码如下：

头文件：

#import <UIKit/UIKit.h>

@interface CSTableViewCell : UIView

+ (CSTableViewCell *)csTableViewCell;
- (void)setTitle:(NSString *)title;

@end

实现文件：

#import "CSTableViewCell.h"

@interface  CSTableViewCell()

@property (weak, nonatomic) IBOutlet UILabel *titleLabel;

@end

@implementation CSTableViewCell

+ (CSTableViewCell *)csTableViewCell
{
    NSArray *views = [[NSBundle mainBundle] loadNibNamed:@"CSTableViewCell" owner:nil options:nil];
    return views[0];
}

//将事件传递给父控件CSTableView处理
- (BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event
{
    return NO;
}

- (void)setTitle:(NSString *)title
{
    self.titleLabel.text = title;
}

步骤二：列表控件CSTableView实现

   关键步骤，如果对列表的运行原理非常了解，下面的代码比较容易理解。需要注意，目前只是简单的采用销毁创建形式实现列表，未采用cell重用机制，后续有时间补上。DataSouce和Delegate参照UITableViewDataSouce和UITableViewDelegate定义，目前只是定义了几个典型的方法。

头文件：

#import <UIKit/UIKit.h>

@class CSTableView;
@class CSTableViewCell;

@protocol CSTableViewDataSource<NSObject>
@required
- (NSInteger)tableView:(CSTableView *)tableView numberOfRowsInSection:(NSInteger)section;
- (CSTableViewCell *)tableView:(CSTableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath;
@end

@protocol CSTableViewDataDelegate <NSObject>
@optional
- (CGFloat)tableView:(CSTableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath;
@end

@interface CSTableView : UIView

@property (nonatomic,assign)id<CSTableViewDataSource> dataSource;
@property (nonatomic,assign)id<CSTableViewDataDelegate> delegate;

+ (CSTableView *)csTableView;
- (void)reloadData;

@end

实现文件：

#import "CSTableView.h"
#import "CSTableViewCell.h"

static const CGFloat kDefaultCellHeight = 27.0f;

@interface CSTableView()
{
    CGPoint _touchBeginPoint;
    CGPoint _touchMovePoint;
    CGPoint _touchEndPoint;
    
    NSInteger   _numberOfRows;
    CGFloat     _top;
    NSInteger   _startIndex;
    NSInteger   _endIndex;
    CGFloat     _startY;
    CGFloat     _dataTotalHeight; //CSTableView的逻辑高度
}

@end

@implementation CSTableView

+ (CSTableView *)csTableView
{
    NSArray *views = [[NSBundle mainBundle] loadNibNamed:@"CSTableView" owner:nil options:nil];
    return views[0];
}

- (void)awakeFromNib
{
    //不能放在这里，此时delegate和dataSource都为nil，之前犯错误了，后面移到了layoutSubviews
    //[self reloadData];
}

- (void)layoutSubviews{
    [self reloadData];
}

#pragma mark -- touches events

- (void)updateUIWithMoveDist:(CGFloat)moveDist
{
    //调控速度
    moveDist = 0.2 * moveDist;
    
    _top += moveDist;
    if (_top < 0) {
        _top = 0;
    }
    if (_dataTotalHeight > self.frame.size.height) {
        if (_top > _dataTotalHeight - self.frame.size.height) {
            _top = _dataTotalHeight - self.frame.size.height;
        }
        [self updateUI];
    }
}

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    UITouch *touch=[touches anyObject];
    _touchBeginPoint = [touch locationInView:self];
}

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
    UITouch *touch=[touches anyObject];
    _touchEndPoint = [touch locationInView:self];
    CGFloat moveDist = _touchBeginPoint.y - _touchEndPoint.y;
    [self updateUIWithMoveDist:moveDist];
}

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
    UITouch *touch=[touches anyObject];
    CGPoint point = [touch locationInView:self];
    CGFloat moveDist =  _touchBeginPoint.y - point.y;
    [self updateUIWithMoveDist:moveDist];
}

#pragma mark -- reloadData

//计算显示范围
- (void)calculateStartIndexAndEndIndex
{
    _startIndex = -1;
    CGFloat totalHeight = 0;
    if ([self.delegate respondsToSelector:@selector(tableView:heightForRowAtIndexPath:)]) {
        for (NSInteger i = 0; i < _numberOfRows; i++) {
            NSIndexPath *indexPath = [NSIndexPath indexPathForRow:i inSection:1];
            CGFloat cellHeight = [self.delegate tableView:self heightForRowAtIndexPath:indexPath];
            totalHeight += cellHeight;
            if (totalHeight > _top && _startIndex == -1) {
                _startY = (totalHeight - cellHeight) - _top;
                _startIndex = i;
            }
            if (totalHeight > _top + self.frame.size.height || i == _numberOfRows - 1) {
                _endIndex = i;
                break;
            }
        }
    }else{
        for (NSInteger i = 0; i < _numberOfRows; i++) {
            totalHeight += kDefaultCellHeight;
            if (totalHeight > _top && _startIndex == -1) {
                _startY = (totalHeight - kDefaultCellHeight) - _top;
                _startIndex = i;
            }
            
            if (totalHeight > _top + self.frame.size.height || i == _numberOfRows - 1) {
                _endIndex = i;
                break;
            }
        }
    }
}

//更新UI
- (void)updateUI
{
    [self calculateStartIndexAndEndIndex];
    NSLog(@"startIndex = %ld", _startIndex);
    NSLog(@"endIndex = %ld", _endIndex);
    
    CGFloat totalHeight = 0.0f;
    for (NSInteger i = _startIndex; i <= _endIndex; i++) {
        //创建cell,如果用户没有自定义cell，则生成一个默认的cell
        CSTableViewCell *cell;
        if ([self.dataSource respondsToSelector:@selector(tableView:cellForRowAtIndexPath:)]) {
            NSIndexPath *indexPath = [NSIndexPath indexPathForRow:i inSection:1];
            cell = [self.dataSource tableView:self cellForRowAtIndexPath:indexPath];
        }else{
            cell = [CSTableViewCell csTableViewCell];
            [cell setTitle:@"默认的cell"];
        }
        
        //设置cell的位置
        if ([self.delegate respondsToSelector:@selector(tableView:heightForRowAtIndexPath:)]) {
                NSIndexPath *indexPath = [NSIndexPath indexPathForRow:i inSection:1];
                CGFloat cellHeight = [self.delegate tableView:self heightForRowAtIndexPath:indexPath];
                totalHeight += cellHeight;
                cell.frame = CGRectMake(0, (totalHeight - cellHeight) + _startY, cell.frame.size.width, cell.frame.size.height);
        }else{
            cell.frame = CGRectMake(0, (i - _startIndex) *kDefaultCellHeight + _startY, cell.frame.size.width, cell.frame.size.height);
        }
        
        //将cell添加到CSTabelView
        [self addSubview:cell];
    }
}

//重新加载数据, 暂时没有采用cell重用机制，后面有时间再加上
//删除数据后，调用该函数，重新加载UI
- (void)reloadData
{
    for (UIView *subView in self.subviews) {
        [subView removeFromSuperview];
    }
    
    if ([self.dataSource respondsToSelector:@selector(tableView:numberOfRowsInSection:)]) {
        _numberOfRows = [self.dataSource tableView:self numberOfRowsInSection:1];
    }else{
        _numberOfRows = 10; //默认显示10条数据
    }
    
    _dataTotalHeight = 0.0f;
    if ([self.delegate respondsToSelector:@selector(tableView:heightForRowAtIndexPath:)]) {
        for (NSInteger i = 0; i < _numberOfRows; i++) {
            NSIndexPath *indexPath = [NSIndexPath indexPathForRow:i inSection:1];
            CGFloat cellHeight = [self.delegate tableView:self heightForRowAtIndexPath:indexPath];
            _dataTotalHeight += cellHeight;
        }
    }else{
        _dataTotalHeight = kDefaultCellHeight * _numberOfRows;
    }
    
    //更新UI
    [self updateUI];
}

@end

#import "RootViewController.h"
#import "CSTableView.h"
#import "CSTableViewCell.h"

@interface RootViewController ()<CSTableViewDataSource, CSTableViewDataDelegate>

@property (nonatomic, strong)CSTableView *csTableView;

@end

@implementation RootViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    self.csTableView = [CSTableView csTableView];
    self.csTableView.dataSource = self;
    self.csTableView.delegate = self;
    self.csTableView.frame = CGRectMake(0, 0, self.csTableView.frame.size.width, self.csTableView.frame.size.height);
    [self.view addSubview:self.csTableView];
}


- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}


#pragma mark -- CSTableViewDataSource
- (NSInteger)tableView:(CSTableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    return 50;
}

- (CSTableViewCell *)tableView:(CSTableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    CSTableViewCell *cell = [CSTableViewCell csTableViewCell];
    NSString *title = [[NSString alloc] initWithFormat:@"测试数据%ld", indexPath.row];
    [cell setTitle:title];
    return cell;
}

#pragma mark -- CSTableViewDataDelegate

- (CGFloat)tableView:(CSTableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
    if (indexPath.row < 10) {
        return 20;
    }else if (indexPath.row >= 10 && indexPath.row < 20){
        return 30;
    }else{
        return 40;
    }
    
    //return 27;
}

@end

iOS开发--自定义列表控件

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原文地址：http://blog.csdn.net/wang_lichun/article/details/45250589