問題描述

我正在使用 nib 文件加載視圖:

I am loading a view from a nib file using:

NSArray *nibViews = [[NSBundle mainBundle] loadNibNamed:@"AnalysisView" owner:self options:nil];
AnalysisView *gridView = [nibViews objectAtIndex: 0];

nib 包含一個名為 gridScrollView 的滾動視圖，在 AnalysisView 實現文件中，我有一個將視圖作為子視圖添加到滾動視圖的方法:

The nib contains a scrollview called gridScrollView and in the AnalysisView implementation file I have a method which adds views as subviews to the scrollview:

for (NSInteger i = [results count] -1; i >= 0; i--) 
{
    Result *result = [results objectAtIndex:i];
    [self loadResult: result];
}

- (void) loadResult: (Result *) result
{
    NSArray *nibViews = [[NSBundle mainBundle] loadNibNamed:@"GridView" owner:self options:nil];
    GridView *gridView = [nibViews objectAtIndex: 0];
    gridView.tag = self.graphCount;

    CGRect gridFrame = gridView.frame;

    CGFloat yOffset = gridFrame.size.height * self.graphCount;
    gridView.frame = CGRectMake(0, yOffset, gridFrame.size.width, gridFrame.size.height);

    [self.gridScrollView addSubview: gridView];
    self.gridScrollView.contentSize = CGSizeMake(self.gridScrollView.frame.size.width, (yOffset + gridFrame.size.height));

    self.graphCount++;
}

我已將滾動視圖委托設置為 AnalysisView 并連接了 do end decelaring 方法

I have set the scrollviews delegate to be AnalysisView and hooked up the did end decelaring method

-(void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
      NSLog(@"%d", [scrollView.subviews count]);
}

當 scrollViewDidEndDecelerating 方法觸發時，它報告子視圖的數量是 5.這些子視圖中的 3 個是我期望的 GridView.但是有 2 個 UIImageViews 我不知道它們為什么在那里.

When the scrollViewDidEndDecelerating method fires it reports that the number of subviews is 5. 3 of these subviews are GridViews which I expect. However there are 2 UIImageViews which I have no idea why they are there.

這是一個問題，因為我打算在 scrollViewDidEndDecelerating 方法中使用 viewWithTag 檢索視圖并在視圖上調用一個方法，但是每當我嘗試檢索標簽為 0 的視圖時，我都會檢索其中一個 UIImageView 和 this導致我的應用程序崩潰，因為無法在圖像視圖上調用該方法.

This is an issue because I intend on retrieving the views with viewWithTag in the scrollViewDidEndDecelerating method and calling a method on the view, however whenever I try to retrieve a view with a tag of 0 I will retrieve one of the UIImageView's and this causes my app to crash because the method cannot be called on an image view.

我知道一種解決方法是將我的 GridView 存儲在一個單獨的實例數組中并從那里引用它們.但我很想知道這 2 個 UIImageView 是什么以及它們是如何到達那里的.

I know a way round this is to store my GridViews in a seperate instance array and reference them from there. But I'm curious to know what the 2 UIImageViews are and how they got there.

推薦答案

UIScrollView 默認包含 2 個 UIImageViews 作為滾動指示器的子視圖.雖然我在文檔中找不到任何關于滾動指示器實現的具體信息，但這些圖像視圖存在于類聲明中(參見 UIScrollView.h 標頭):

UIScrollView by default contains 2 UIImageViews as subviews for scroll indicators. Although I can't find anything specific about scroll indicators implementation in docs, those imageviews are present in class declaration (see UIScrollView.h header):

UIKIT_CLASS_AVAILABLE(2_0) @interface UIScrollView : UIView <NSCoding> {
    ...
    UIImageView* _verticalScrollIndicator;
    UIImageView* _horizontalScrollIndicator;

您也可以不從 0 開始分配標簽，而是從某個正數開始 - 這樣可以避免與標準子視圖發生沖突

You can also start assigning tags not from 0, but from some positive number - that way avoiding collision with standard subviews

這篇關于UIScrollView 幻象子視圖的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網！