insertSubview：AtIndex：不起作用

Question

我浏览了有关这个问题的材料，但仍然无法完全弄清楚。 主要问题是我正在使用这种方法，但视图没有显示...... 该应用程序由两个视图构建 - 主视图（我将其作为子视图添加到主笔尖） - 有一个文本字段，我可以在其中写一些文本。 有一个按钮，按下该按钮时，操作方法会加载第二个视图，其中有一个标签，其中包含一些文本。 第一个viewController的源代码：

#import <UIKit/UIKit.h>

@class TxtRunnerViewController;

@interface Itai_s_text_app_take_2ViewController : UIViewController {
 int sliderSpeed;
 IBOutlet UITextField  *textInput;
 TxtRunnerViewController *trvc;
}

@property (nonatomic, retain) IBOutlet UITextField *textInput;
@property (retain, nonatomic) TxtRunnerViewController *trvc;

- (IBAction)sliderChanged:(id)sender;//speed of text show changed

- (IBAction)textFieldDoneEditing:(id)sender;//dor 'DONE' on keyboard
- (IBAction)backgroundTap:(id)sender;//for handling tapping on background

- (IBAction)textEmButtonPressed:(id)sender;

@end

第一个ViewController的.m： #import“Itai_s_text_app_take_2ViewController.h” #import "TxtRunnerViewController.h"

@implementation Itai_s_text_app_take_2ViewController
@synthesize textInput;
@synthesize trvc;


- (IBAction)sliderChanged:(id)sender
{
 UISlider *slider = (UISlider *)sender;
 sliderSpeed =  (int)(slider.value + 0.5f);//setting the speed determinned by the usr in slider
 NSLog(@"Slider value is %@", sliderSpeed);
}

- (IBAction)textFieldDoneEditing:(id)sender
{
    [sender resignFirstResponder];
 NSLog(@"our text input  is %@", textInput.text);
}

- (IBAction)backgroundTap:(id)sender
{
 [textInput resignFirstResponder]; 
}

- (IBAction)textEmButtonPressed:(id)sender
{
 NSLog(@"button pressed");
 if ([textInput.text length]==0) 
 {
  NSString *msg = nil;
  msg = @"Write text to transmit";
  UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Forgot something?"
              message:msg
                delegate:self
             cancelButtonTitle:@"Back" 
             otherButtonTitles:nil];

  [alert show]; 
  [alert release]; 
  [msg release];
 }
 else { //init 
  NSLog(@"HI!");
  if (self.trvc == nil)
  {
   NSLog(@"if accepted");
   TxtRunnerViewController *tr = [[TxtRunnerViewController alloc] initWithNibName:@"TxtRunner"
                       bundle:nil];
   self.trvc = tr;
   [tr release];
  }
  [self.view removeFromSuperview];
  [self.view insertSubview:trvc.view atIndex:0];
  NSLog(@"InsertAtIndex was operated...!");
  //[self.view addSubview:tvc.view];
 }

}
/*
// The designated initializer. Override to perform setup that is required before the view is loaded.
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}
*/

/*
// Implement loadView to create a view hierarchy programmatically, without using a nib.
- (void)loadView {
}
*/


/*
// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
- (void)viewDidLoad {
    [super viewDidLoad];
}
*/


/*
// Override to allow orientations other than the default portrait orientation.
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
    // Return YES for supported orientations
    return (interfaceOrientation == UIInterfaceOrientationPortrait);
}
*/

- (void)didReceiveMemoryWarning {
 // Releases the view if it doesn't have a superview.
    [super didReceiveMemoryWarning];

 // Release any cached data, images, etc that aren't in use.
 if(self.trvc.view.superview == nil)
  self.trvc = nil;
}

- (void)viewDidUnload {
 // Release any retained subviews of the main view.
 // e.g. self.myOutlet = nil;
}


- (void)dealloc {
 [trvc release];
    [super dealloc];
}

第二个视图只是空的（在它的 nib 文件中添加了一个标签）： #import

@interface TxtRunnerViewController : UIViewController {

}

@end

它的.m文件是默认的，没有添加任何代码。 当我在第一个视图中按下按钮时 - 它的视图消失，但第二个视图没有出现，只出现一个空白的白色视图，上面什么也没有。

美国能源部

Answer 1

如果您推送 TxtRunnerViewController 它将完全隐藏第一个，但它仍然存在于后台。 （没有removeFromSuperview）

TxtRunnerViewController *vw = [[TxtRunnerViewController alloc]initWithNibName:@"TxtRunner" bundle:nil];
[self.view pushViewController:vw.view animated:NO];
[vw release];

要删除第一个视图有点困难。您需要在 RootViewController 中实现一个委托，该委托将在单击第一个视图的完成按钮后被触发。然后在 RootViewController 中执行一些代码，显示第二个视图并删除第一个视图。

对于委托示例，在创建新项目时打开实用程序应用程序示例并了解其工作原理或在线搜索一些示例。

Answer 2

该行：
[self.viewremoveFromSuperview];

从其超级视图中删除视图

，然后调用

[self.view insertSubview:trvc.view atIndex:0];

向其添加 trvc - 但该视图已被删除并且不再可见。

您需要将 trvc 添加到超级视图中。