Question

一堂课：

在以下方法中，我使用块来替换公共委托。好吗？ didSelectRowAtIndexPath方法中的块，我使用它替换公共委托，但如果它运行，我单击表格单元格，代码崩溃。

typedef void (^Block)(NSString *id,NSString *cityName);
@interface WLCCityListViewController : WLCBaseSquareViewController <UITableViewDataSource,UITableViewDelegate>
{   
    Block _block;
    id<commonDelegate>delegate;
}

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil Block:(Block)block
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        _block=block;
    }
    return self;
}        

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
    WLCMainViewCityListData *data=[[self citylists]objectAtIndex:[indexPath section]];
    //    [self.delegate seleteCityID:[[data.cityList objectAtIndex:indexPath.row]objectForKey:@"id"]  CityName:[[data.cityList objectAtIndex:indexPath.row]objectForKey:@"name"]];
    NSString *a1 =[[data.cityList objectAtIndex:indexPath.row]objectForKey:@"id"];

    NSString *a2 =[[data.cityList objectAtIndex:indexPath.row]objectForKey:@"name"];
    _block(a1,a2);    
}

B班：

@interface WLCMainViewController : WLCBaseSquareViewController
{
}
@implementation WLCMainViewController

-(void)viewDidLoad {
    WLCCityListViewController *tableViewController = [[[WLCCityListViewController alloc]initWithNibName:@"WLCCityListViewController" bundle:nil Block:^(NSString *id, NSString *cityName) {
        self.cityID=id;
        WLCMainViewModel *model=(WLCMainViewModel *)self.mainviewModel;
        model.cityID=id;
        [model sendRequest];
        [self.view startWaiting];
    }] autorelease];
}

Answer 1

_block = block;

此行导致崩溃。你只是分配一个块但不保留它。不使用保留，只使用副本。声明一个复制属性。

@property (nonatomic, copy) Block _block;

并使用setter。或者只是改变你这样的代码。

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil Block:  (Block)block
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
    //_block=block;
    _block = block? [[block copy] autorelease]: nil;
}
return self;

}

Answer 2

您可以将块视为OC对象通常，如果您需要保留块，请使用Block_copy执行此操作，并且不要忘记阻止它释放它你的代码的问题是当你调用它时块是自动释放的。

如何使用块替换常见委托

2 个答案: