ios开发 Block(二) 实现委托

委托和block是IOS上实现回调的两种机制。Block基本可以代替委托的功能，而且实现起来比较简洁，比较推荐能用block的地方不要用委托。

实现效果如图

第一步，自定义CustomCell

#import <Foundation/Foundation.h>

@interface CustomCell : UITableViewCell

@property (strong, nonatomic) IBOutlet UILabel *labName;
@property (copy,nonatomic) void(^BuyGoods)(NSString *);

- (IBAction)ButtonBuyPressed:(id)sender;

@end

#import "CustomCell.h"

@implementation CustomCell



- (IBAction)ButtonBuyPressed:(id)sender {
    
    NSString *goodName=_labName.text;
    _BuyGoods(goodName);
    
}

@end

在custom.h文件里面有

@property (copy,nonatomic) void(^BuyGoods)(NSString *);

声明了一个block变量

在custom.m文件里面回调

 NSString *goodName=_labName.text;

 _BuyGoods(goodName);

下面看实现的类里面

#import "ViewController.h"
#import "CustomCell.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    
    _tabGoods.delegate=self;
    _tabGoods.dataSource=self;
}

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

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *CellIdentifier = @"CustomCell";
    CustomCell *cell = (CustomCell*)[tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    if (cell == nil) {
        NSArray *nib = [[NSBundle mainBundle] loadNibNamed:@"CustomCell" owner:self options:nil];
        cell = [nib objectAtIndex:0];
    }
    cell.labName.text = [NSString stringWithFormat:@"商品名称%d",indexPath.row];
    __block NSString *tipMsg=cell.labName.text;
    cell.BuyGoods=^(NSString *str){
        UIAlertView *alertView=[[UIAlertView alloc]initWithTitle:@"提示内容" message:tipMsg delegate:nil cancelButtonTitle:@"取消" otherButtonTitles:nil, nil];
        [alertView show];
    };
    
    return cell;
}

-(NSInteger)numberOfSectionsInTableView:(UITableView *)tableView{
    return 1;
}

-(NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{
    return 10;
}

@end

在ViewController.m文件里面

 __block NSString *tipMsg=cell.labName.text;

    cell.BuyGoods=^(NSString *str){

        UIAlertView *alertView=[[UIAlertView alloc]initWithTitle:@"提示内容" message:tipMsg delegate:nil cancelButtonTitle:@"取消" otherButtonTitles:nil, nil];

        [alertView show];

    };

实现Block里面的代码块，__block NSString *tipMsg=cell.labName.text;这一行保证变量能在block代码块里面使用.........

运行效果图: