在UIPickerView中加載數據之前，它出現

Question

我在一個模式視圖中的視圖控制器中使用UIPickerView（如果這就是它的名稱）。 我讀過的所有地方[picker reloadAllComponents];在viewDidLoad應該做的伎倆，但它沒有。我已經覆蓋-(UIView*)viewForRow-方法，但我不認爲這應該是問題..

事情是，當viewController垂直彈出，選擇器是空的。直到我向下滾動，才能出現新的一行。但是，如果我將[picker reloadAllComponents];添加到viewDidAppear，那麼在viewController完成其介入動畫（垂直）後立即顯示數據。儘管這很煩人。我希望選取器在滑動時已經擁有數據。

我試着把reloadAllComponents都放在viewDidLoad和viewWillAppear之間，但它不起作用。

我把一個NSLog放在委託方法中，它打印出正確的數據，它在視圖彈出之前就做到了，但爲什麼不顯示它呢？

我以前有過和tableViewController相同的問題，我認爲reloadData那麼做了，但爲什麼它不會在viewDidLoad中繪製我的視圖？它只做它，如果它被稱爲在viewDIDappear ..

代碼：

-(NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView 
{ 
    return 2; 
} 
-(NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component 
{ 
    if(component == TYPE1) 
     return [[con getTypes] count]; 

    else return 1; 

} 
-(UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view 
{ 
    UIView* newView = [[UIView alloc] init]; 

    //Create a label, put it on the left side of the view 
    UILabel *label = [[UILabel alloc]initWithFrame:CGRectMake(view.frame.origin.x + 5, view.frame.origin.y, view.frame.size.width-45, view.frame.size.height)]; 
    [label setText:[[[con getTypes] objectAtIndex:row] getName]]; 
    [newView addSubview:label];//add 

    //Create an imageview, put it on the right side of the view 
    UIImageView*imageViewType = [[UIImageView alloc] initWithFrame:CGRectMake(view.frame.origin.x+(view.frame.size.width-40), view.frame.origin.y, 40, 40)]; 
    [imageViewType setImage:[[[con getTypes] objectAtIndex:row] getImage]]; 
    [newView addSubview:imageViewType];//add 

    [label setBackgroundColor:[UIColor clearColor]]; 


    NSLog(@"%@", [[[con getTypes]objectAtIndex:row] getName]); 
    //This NSLog prints out the correct name for the top three items of the list 
    //-even when called from viewDidLoad, and even before the view appears, but 
    //the content never shows up in the picker unless I scroll or call it again in 
    //viewDidAppear.. 

    return newView; 
} 

Answer 1

-(UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view 
{ 
    UIView* newView; 

    if (view) 
     newView = view; 
    else { 
     newView = [[UIView alloc] initWithFrame:CGRectMake(0,0,250,50)]; // use some appropriate size hier. I just made some figures up which almost certainly will not work. 
     //Create a label, put it on the left side of the view 
     UILabel *label = [[UILabel alloc]initWithFrame:CGRectMake(5.0f, 0.0f, newView.frame.size.width-45, newView.frame.size.height)]; 
     [newView addSubview:label];//add 

    //Create an imageview, put it on the right side of the view 
     UIImageView*imageViewType = [[UIImageView alloc] initWithFrame:CGRectMake((newView.frame.size.width-40.0f), 0.0f, 40.0f, 40.0f)]; 
     [newView addSubview:imageViewType];//add 
    } 

    [label setText:[[[con getTypes] objectAtIndex:row] getName]]; 
    [label setBackgroundColor:[UIColor clearColor]]; 

    [imageViewType setImage:[[[con getTypes] objectAtIndex:row] getImage]]; 

    return newView; 
}