解决tableView中cell动态加载控件的重用问题

解决tableView中cell动态加载控件的重用问题

tableView的cell,有时候需要在运行时取得对应的数据后才能够动态的创建该cell中的控件并加载到该cell中,此时,你一定会遇到重用问题,即使你能做到该cell只根据数值加载了一回控件,你也没法保证不出现重用问题:)

效果(请注意查看,移动下面的格子时,上面出现了重用的问题)

源码:

YXCell.h

//
//  YXCell.h
//  YXTableView
//
//  Copyright (c) 2014年 Y.X. All rights reserved.
//

#import <UIKit/UIKit.h>

@interface YXCell : UITableViewCell

@property (nonatomic, strong) NSString *count; // 控件个数
@property (nonatomic, assign) BOOL      flag;  // 控制标签

@end

YXCell.m

//
//  YXCell.m
//  YXTableView
//
//  Copyright (c) 2014年 Y.X. All rights reserved.
//

#import "YXCell.h"

@implementation YXCell

- (id)initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(NSString *)reuseIdentifier
{
    self = [super initWithStyle:style reuseIdentifier:reuseIdentifier];
    if (self)
    {

    }
    return self;
}

@synthesize count = _count;
- (void)setCount:(NSString *)count
{
    if ([count intValue] > 0 && _flag == NO)
    {
        _flag = YES;

        UIScrollView *scrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 0, 320, 100)];
        scrollView.contentSize = CGSizeMake([count intValue]*100, 100);
        
        for (int i = 0; i < [count intValue]; i++)
        {
            UILabel *tmpLabel = [[UILabel alloc] initWithFrame:CGRectMake(i*100, 0, 100, 100)];
            tmpLabel.text     = [NSString stringWithFormat:@"%d", i];
            tmpLabel.textAlignment = NSTextAlignmentCenter;
            tmpLabel.font     = [UIFont fontWithName:@"HelveticaNeue-UltraLight"
                                                size:40.f];
            [scrollView addSubview:tmpLabel];
        }
        
        [self addSubview:scrollView];
    }
    
    _count = count;
}

@end

RootViewController.m

//
//  RootViewController.m
//  YXTableView
//
//  Copyright (c) 2014年 Y.X. All rights reserved.
//

#import "RootViewController.h"
#import "YXCell.h"



#define REUESED_SIZE  100
static NSString *reUsedStr[REUESED_SIZE] = {nil}; // 重用标示
#define REUESED_FLAG  reUsedStr[0]


@interface RootViewController ()<UITableViewDataSource, UITableViewDelegate>

@property (nonatomic, strong) UITableView  *mainTableView;
@property (nonatomic, strong) NSArray      *dataArray;

@end

@implementation RootViewController

+ (void)initialize
{
    if (self == [RootViewController class])
    {
        for (int i = 0; i < REUESED_SIZE; i++)
        {
            reUsedStr[i] = [NSString stringWithFormat:@"YouXianMing_%d", i];
        }
    }
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    
    // 数据源
    _dataArray = @[[NSString stringWithFormat:@"%d", arc4random()%20 + 5],
                   [NSString stringWithFormat:@"%d", arc4random()%20 + 5],
                   [NSString stringWithFormat:@"%d", arc4random()%20 + 5],
                   [NSString stringWithFormat:@"%d", arc4random()%20 + 5],
                   [NSString stringWithFormat:@"%d", arc4random()%20 + 5],
                   [NSString stringWithFormat:@"%d", arc4random()%20 + 5],
                   [NSString stringWithFormat:@"%d", arc4random()%20 + 5],
                   [NSString stringWithFormat:@"%d", arc4random()%20 + 5],
                   [NSString stringWithFormat:@"%d", arc4random()%20 + 5],
                   [NSString stringWithFormat:@"%d", arc4random()%20 + 5],
                   [NSString stringWithFormat:@"%d", arc4random()%20 + 5],
                   [NSString stringWithFormat:@"%d", arc4random()%20 + 5],
                   [NSString stringWithFormat:@"%d", arc4random()%20 + 5],
                   [NSString stringWithFormat:@"%d", arc4random()%20 + 5],
                   [NSString stringWithFormat:@"%d", arc4random()%20 + 5],
                   [NSString stringWithFormat:@"%d", arc4random()%20 + 5],
                   [NSString stringWithFormat:@"%d", arc4random()%20 + 5],
                   [NSString stringWithFormat:@"%d", arc4random()%20 + 5],
                   [NSString stringWithFormat:@"%d", arc4random()%20 + 5],
                   [NSString stringWithFormat:@"%d", arc4random()%20 + 5],
                   [NSString stringWithFormat:@"%d", arc4random()%20 + 5],
                   [NSString stringWithFormat:@"%d", arc4random()%20 + 5],
                   [NSString stringWithFormat:@"%d", arc4random()%20 + 5],
                   [NSString stringWithFormat:@"%d", arc4random()%20 + 5]];
    
    // UITableView
    _mainTableView = [[UITableView alloc] initWithFrame:self.view.bounds
                                                  style:UITableViewStylePlain];
    _mainTableView.delegate   = self;
    _mainTableView.dataSource = self;
    [self.view addSubview:_mainTableView];
}


#pragma mark - UITableView delegate dataSource
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    return [_dataArray count];
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    YXCell *cell = [tableView dequeueReusableCellWithIdentifier:REUESED_FLAG];
    if (cell == nil)
    {
        cell = [[YXCell alloc] initWithStyle:UITableViewCellStyleDefault
                             reuseIdentifier:REUESED_FLAG];
    }
    
    cell.count = _dataArray[indexPath.row];
    
    return cell;
}

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
    return 100;
}

@end

几个比较关键的地方:

本例中出现的重用问题由下面部分引发:

如果要解决这个重用问题,我们只能够让这个cell不重用,那就得定义足够多的重用标示才行,改成如下即可:

效果:

总结:

为何要处心积虑弄这种不重用的cell呢?当然,这是为了满足特定的需求而出现的适合于少量的cell的情形,对于这种动态加载的cell,你亲自动手试一下或许就能明白作者本人为何如此设计的用心良苦:)