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
@endYXCell.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;
}
@endRootViewController.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:)
