cell的循环利用

方式一

#import "ViewController.h"

@interface ViewController ()<UITableViewDataSource>

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    UITableView *tableView=[[UITableView alloc]init];
    tableView.frame=self.view.bounds;
    
    tableView.rowHeight=70;
    tableView.dataSource=self;
    [self.view addSubview:tableView];
}

#pragma mark-<UITableViewDataSource>
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    return 50;
    
}

// Row display. Implementers should *always* try to reuse cells by setting each cell's reuseIdentifier and querying for available reusable cells with dequeueReusableCellWithIdentifier:
// Cell gets various attributes set automatically based on table (separators) and data source (accessory views, editing controls)


- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString  *ID=@"a";
  UITableViewCell *cell=  [tableView dequeueReusableCellWithIdentifier:ID];
    
    if(cell==nil)
    {
        cell=[[UITableViewCell alloc]initWithStyle:UITableViewCellStyleDefault reuseIdentifier:ID];
    }
    
    cell.textLabel.text=[NSString stringWithFormat:@"testdata--%zd",indexPath.row];
    
    
    return cell;
}



@end
0w2bbg bms

tableView的性能优化-cell的循环利用方式2

-定义一个全局变量

NSString *ID=@"hero";

-注册某个表示对应的cell类型

- (void)viewDidLoad {
    [super viewDidLoad];
    [self.tableView registerClass:[UITableViewCell class] forCellReuseIdentifier:ID];
    
}

在数据方法中找到cell

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:ID];
    
    XMGHero *hero = self.heroes[indexPath.row];
    
    cell.textLabel.text = hero.name;
    cell.imageView.image = [UIImage imageNamed:hero.icon];
    cell.detailTextLabel.text = hero.intro;
    
    return cell;
}