從supreview中刪除，只有它存在

Question

我在空閒時間工作在ipad上，我碰到過一個小問題。在我uisplitview，如果我點擊一個細胞，它加載的圖片，我有另外兩個單元，每個單元有此代碼爲點擊

[self.icon1 removeFromSuperview]; 

時能正常工作，但去掉圖片。如果之後我點擊單元格與圖片...然後我單擊單元格2（和此刪除代碼運行）它正確地刪除圖片。但如果我點擊單元格3 ...則程序中斷（訪問不良，它指向removeFromSuperview）。而我認爲這是因爲圖標已被刪除。基本上說有沒有一個功能說「如果存在然後從superview中刪除」？ 謝謝

if (([receivedRainObject isEqualToString:@"Facts"]) && (Track==100)) { 
    self.view.backgroundColor=[UIColor whiteColor]; 
    //  self.tvFacts=[[UITextView alloc]initWithFrame:CGRectMake(0, 150, 700, 500)]; 
    self.tvFacts.text=@" Test"; 

    [tvFacts setEditable:NO]; 

    UIImage *acheivement1=[UIImage imageNamed:@"saychesse.png"]; 
    [factBanner1 setImage:acheivement1]; 

    UIImage *fbIcon= [UIImage imageNamed:@"facebook.png"]; 
    fbIcon1 = [UIButton buttonWithType:UIButtonTypeCustom]; 
    fbIcon1.frame = CGRectMake(580.0, 305.0, 35.0, 35.0); 
    fbIcon1.tag=TAG_BUTTON_ONE; 
    [fbIcon1 addTarget:self action:@selector(authButtonAction) forControlEvents:UIControlEventTouchUpInside]; 
    [fbIcon1 setBackgroundImage:fbIcon forState:UIControlStateNormal]; 

    UIImage *twIcon= [UIImage imageNamed:@"twitter.png"]; 
    twIcon1 = [UIButton buttonWithType:UIButtonTypeCustom]; 
    twIcon1.frame = CGRectMake(530.0, 305.0, 35.0, 35.0); 
    [twIcon1 addTarget:self action:@selector(tweetTapped) forControlEvents:UIControlEventTouchUpInside]; 
    [twIcon1 setBackgroundImage:twIcon forState:UIControlStateNormal]; 

    [self.imgClassification removeFromSuperview]; 
    [self.Image removeFromSuperview]; 

    [self.lblSel removeFromSuperview]; 
    [self.tvDescrip removeFromSuperview]; 
    [self.tvName removeFromSuperview]; 
    [self.tvDiet removeFromSuperview]; 
    [self.navigationController popViewControllerAnimated:NO]; 
    [self.lblPictureAnnotation removeFromSuperview]; 
    [self.lbllife removeFromSuperview]; 
    [self.tvGestation removeFromSuperview]; 

    [self.view addSubview:self.tvFacts]; 
    [self.view addSubview:factBanner1]; 
    [self.view addSubview:fbIcon1]; 
    [self.view addSubview:twIcon1]; 
    [self.view setNeedsDisplay]; 

} 
// Life-Span   
if (([receivedRainObject isEqualToString:@"Life Span"]) && (Track==100)) { 
    self.view.backgroundColor=[UIColor whiteColor]; 
    //  self.lbllife=[[UILabel alloc]initWithFrame:CGRectMake(0, 150, 700, 500)]; 
    self.lbllife.text=@"The"; 

    [lbllife setEditable:NO]; 
    [self.factBanner1 removeFromSuperview]; 
    [self.fbIcon1 removeFromSuperview]; 
    [self.twIcon1 removeFromSuperview]; 
    [self.factBanner2 removeFromSuperview]; 
     [self.fbIcon2 removeFromSuperview]; 
    [self.twIcon2 removeFromSuperview]; 
    [self.imgClassification removeFromSuperview]; 
    [self.Image removeFromSuperview]; 

    [self.lblSel removeFromSuperview]; 
    [self.tvDescrip removeFromSuperview]; 
    [self.tvName removeFromSuperview]; 
    [self.tvDiet removeFromSuperview]; 
    [self.navigationController popViewControllerAnimated:NO]; 
    [self.tvFacts removeFromSuperview]; 
    [self.lblPictureAnnotation removeFromSuperview]; 
    [self.tvGestation removeFromSuperview]; 
    [self.factBanner1 removeFromSuperview]; 
    [self.view addSubview:self.lbllife]; 
    [self.view setNeedsDisplay];   
} 

Answer 1

我的猜測是，你已經在某個時候刪除從它的父self.icon1和icon1屬性是weak參考。

這意味着icon1只保留其超級視圖。因此，第一次將其刪除後，它會被釋放，當您嘗試第二次使用它時，會出現錯誤。

解決方案：將icon1屬性更改爲strong引用或（更好），後[self.icon1 removeFromSuperview];。

順便說一句，這是Clang靜態分析儀（運行它與Product > Analyze）通常能夠檢測到的那種錯誤。