ios開發 Block(二) 實現委託

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委託和block是IOS上實現回調的兩種機制。Block基本可以代替委託的功能，而且實現起來比較簡潔，比較推薦能用block的地方不要用委託。

實現效果

第一步，自訂CustomCell

 1 #import <Foundation/Foundation.h> 2  3 @interface CustomCell : UITableViewCell 4  5 @property (strong, nonatomic) IBOutlet UILabel *labName; 6 @property (copy,nonatomic) void(^BuyGoods)(NSString *); 7  8 - (IBAction)ButtonBuyPressed:(id)sender; 9 10 @end

 1 #import "CustomCell.h" 2  3 @implementation CustomCell 4  5  6  7 - (IBAction)ButtonBuyPressed:(id)sender { 8      9     NSString *goodName=_labName.text;10     _BuyGoods(goodName);11     12 }13 14 @end

在custom.h檔案裡面有

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

聲明了一個block變數

在custom.m檔案裡面回調

 NSString *goodName=_labName.text;

 _BuyGoods(goodName);

下面看實現的類裡面

 1 #import "ViewController.h" 2 #import "CustomCell.h" 3  4 @interface ViewController () 5  6 @end 7  8 @implementation ViewController 9 10 - (void)viewDidLoad11 {12     [super viewDidLoad];13     // Do any additional setup after loading the view, typically from a nib.14     15     _tabGoods.delegate=self;16     _tabGoods.dataSource=self;17 }18 19 - (void)didReceiveMemoryWarning20 {21     [super didReceiveMemoryWarning];22     // Dispose of any resources that can be recreated.23 }24 25 - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath26 {27     static NSString *CellIdentifier = @"CustomCell";28     CustomCell *cell = (CustomCell*)[tableView dequeueReusableCellWithIdentifier:CellIdentifier];29     if (cell == nil) {30         NSArray *nib = [[NSBundle mainBundle] loadNibNamed:@"CustomCell" owner:self options:nil];31         cell = [nib objectAtIndex:0];32     }33     cell.labName.text = [NSString stringWithFormat:@"商品名稱%d",indexPath.row];34     __block NSString *tipMsg=cell.labName.text;35     cell.BuyGoods=^(NSString *str){36         UIAlertView *alertView=[[UIAlertView alloc]initWithTitle:@"提示內容" message:tipMsg delegate:nil cancelButtonTitle:@"取消" otherButtonTitles:nil, nil];37         [alertView show];38     };39     40     return cell;41 }42 43 -(NSInteger)numberOfSectionsInTableView:(UITableView *)tableView{44     return 1;45 }46 47 -(NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{48     return 10;49 }50 51 @end

在ViewController.m檔案裡面

 __block NSString *tipMsg=cell.labName.text;

    cell.BuyGoods=^(NSString *str){

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

        [alertView show];

    };

實現Block裡面的代碼塊，__block NSString *tipMsg=cell.labName.text;這一行保證變數能在block代碼塊裡面使用.........

運行:

ios開發 Block(二) 實現委託