cocoa-touch - TTModel 加载方法未被调用

Question

问题

描述

以下代码导致 TTModel 的 load 方法未被调用。我已单步执行调试器以及 TTCatalog 应用程序。我可以看到两者之间的唯一区别是，当目录在 Controller 的 createModel 方法中设置其数据源时，TTModel 的 load 方法被调用，而我的则被调用不是。

关于代码

我对代码的特定区域进行了注释，以告诉他们应该做什么以及发生了什么问题，但为了完整起见，我将所有内容都包含在内。

你应该具体看看

• PositionsController 的 createModel 方法
• PositionsList 的 load 方法

这些是问题所在的领域，也是最好的起点。

<小时/>

代码

PositionsController:TTTableViewController

- (id)initWIthNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{

    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];

    if (self)
    {
        self.title = @"Positions";
        self.variableHeightRows = NO;
        self.navigationBarTintColor = [UIColor colorWithHexString:@"1F455E"];
    }

    return self;
}

//This method here should result in a call to the PositionsList load method
- (void)createModel
{
    PositionsDataSource *ds = [[PositionsDataSource alloc] init];
    self.dataSource = ds;
    [ds release];
}

- (void)loadView
{
    [super loadView];
    self.view = [[[UIView alloc] initWithFrame:TTApplicationFrame()] autorelease];
    self.tableView = [[[UITableView alloc] initWithFrame:TTApplicationFrame() style:UITableViewStylePlain] autorelease];
    self.tableView.backgroundColor = [UIColor colorWithHexString:@"E2E7ED"];
    self.tableView.separatorColor = [UIColor whiteColor];
    self.tableView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
    //self.tableView.delegate = self;
    [self.view addSubview:self.tableView];
}

//Override UITableViewDelegate creation method, so we can add drag to refresh
- (id<TTTableViewDelegate>) createDelegate {

    TTTableViewDragRefreshDelegate *delegate = [[TTTableViewDragRefreshDelegate alloc] initWithController:self];

    return [delegate autorelease];
}

PositionsDataSource:TTListDataSource

@implementation PositionsDataSource

@synthesize positionsList = _positionsList;

-(id)init
{
    if (self = [super init]) 
    {
        _positionsList = [[PositionsList alloc] init];
        self.model = _positionsList;
    }
    return self;
}

-(void)dealloc
{
    TT_RELEASE_SAFELY(_positionsList);
    [super dealloc];
}

-(void)tableViewDidLoadModel:(UITableView*)tableView
{
    self.items = [NSMutableArray array];
}

-(id<TTModel>)model
{
    return _positionsList;
}
@end

位置列表:NSObject <TTModel >

@implementation PositionsList

//============================================================
//NSObject

- (id)init
{
    if (self = [super init])
    {
        _delegates = nil;
        loaded = NO;
        client = [[Client alloc] init];
    }
    return self;
}

- (void)dealloc
{
    TT_RELEASE_SAFELY(_delegates);
    [client dealloc];
    [super dealloc];
}

//==============================================================
//TTModel

- (NSMutableArray*)delegates
{
    if (!_delegates)
    {
        _delegates = TTCreateNonRetainingArray();
    } 
    return _delegates;
}

-(BOOL)isLoadingMore
{
    return NO;
}

-(BOOL)isOutdated
{
    return NO;
}

-(BOOL)isLoaded
{
    return loaded;
}

-(BOOL)isEmpty
{
    //return !_positions.count;
    return NO;
}

-(BOOL)isLoading
{
    return YES;
}

-(void)cancel
{
}

//This method is never called, why is that?
-(void)load:(TTURLRequestCachePolicy)cachePolicy more:(BOOL)more
{
    //This method is not getting called
    //When the PositionsController calls self.datasource, load should be called,
    //however it isn't.
    [_delegates perform:@selector(modelDidStartLoad:) withObject:self];
    [client writeToServer:self dataToSend:@""];
}

-(void)invalidate:(BOOL)erase
{
}

@end

Answer 1

简短回答:对于您的 PositionList 中的 isLoading，返回 NO 而不是 YES。

更详细的解释:

如果您仔细研究 Three20 源代码，您会发现在 View Controller 上设置数据源会设置模型，刷新模型并可能调用加载。以下是 TTModelViewController 刷新时调用的代码:

- (void)refresh {
  _flags.isViewInvalid = YES;
  _flags.isModelDidRefreshInvalid = YES;

  BOOL loading = self.model.isLoading;
  BOOL loaded = self.model.isLoaded;
  if (!loading && !loaded && [self shouldLoad]) {
    [self.model load:TTURLRequestCachePolicyDefault more:NO];

  } else if (!loading && loaded && [self shouldReload]) {
    [self.model load:TTURLRequestCachePolicyNetwork more:NO];

  } else if (!loading && [self shouldLoadMore]) {
    [self.model load:TTURLRequestCachePolicyDefault more:YES];

  } else {
    _flags.isModelDidLoadInvalid = YES;
    if (_isViewAppearing) {
      [self updateView];
    }
  }
}

您的 PositionList 对象对于 isLoading 返回 YES，对于 isLoaded 返回 NO。这意味着 Three20 认为您的模型正在加载，但实际上并未加载。如果默认情况下不返回 YES，您可能还需要实现 shouldLoad。