Question

我希望在主窗口上显示按下信息按钮时创建的modalViewController视图。但是当我按下主窗口上的“信息”按钮时，没有任何反应。

在mainviewcontroller.h文件中，我有以下代码：

#import <UIKit/UIKit.h>
#import <AVFoundation/AVFoundation.h>

@interface imageviewViewController : UIViewController{
AVAudioPlayer *audioPlayer;
}

@property (nonatomic, retain) UIToolbar *toolbar;
@property (nonatomic, assign) UIBarButtonSystemItem currentSystemItem;
@property (nonatomic, retain) AVAudioPlayer *audioPlayer;

@end

在mainviewcontroller.m文件中有以下代码：

#import "imageviewViewController.h"
#import "Infoviewcontroller.h"


@implementation imageviewViewController

@synthesize toolbar;
@synthesize currentSystemItem;
@synthesize audioPlayer;

UIBarButtonItem *infoItem = [[UIBarButtonItem alloc] 
                          initWithTitle:@"Info" 
                          style:UIBarButtonItemStyleBordered 
                          target:nil 
                          action:@selector(Infobuttonpressed)]; 

  // flex item used to put space in between buttons

    UIBarButtonItem *flexItem = [[UIBarButtonItem alloc] 
                             initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace
                             target:nil
                             action:nil];

    //Add buttons to the array

    NSArray *toolbarItems = [NSArray arrayWithObjects: settingsButton, flexItem, systemItem, flexItem, systemItem1,flexItem, systemItem2, flexItem, systemItem3, flexItem, infoItem, nil];

     [toolbar setItems:toolbarItems];

    [settingsButton release];
    [systemItem  release];
    [systemItem1 release];
    [systemItem2 release];
    [systemItem3 release];
    [infoItem release];
    [flexItem release];

[super viewDidLoad];  

}


- (void) Infobuttonpressed: (id) sender
{
Infoviewcontroller *myView = [[Infoviewcontroller alloc] init];
[self presentModalViewController:myView animated:YES]; // present view modally
[self.navigationController pushViewController:myView animated:YES]; // add to navigation stack
[myView release];
}

在Infoviewcontroller.h文件中有以下代码：

#import <UIKit/UIKit.h>

@interface Infoviewcontroller : UIViewController <UITextViewDelegate>

{

UITextView *textView;

}

@property (nonatomic, retain) UITextView *textView;
@property (nonatomic, assign) UINavigationBar *navBar;


@end

然后在infoviewcontroller.m文件中输入以下代码：

#import "Infoviewcontroller.h"

@implementation Infoviewcontroller

@synthesize textView;
@synthesize navBar;



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

 -(void)setupTextView
  {
self.textView = [[[UITextView alloc] initWithFrame:self.view.frame] autorelease];

self.textView.textColor = [UIColor redColor];

self.textView.font = [UIFont fontWithName:@"System Bold" size:13];

self.textView.delegate = self;

self.textView.backgroundColor = [UIColor whiteColor];

self.textView.textAlignment =  UITextAlignmentCenter;

self.textView.text = @"This is UITextView\nThis is UITextView\nThis is UITextView\nThis is UITextView"; 

[self.view addSubview: self.textView];    

}

- (void)viewDidLoad
{
[super viewDidLoad];

navBar = [[UINavigationBar alloc] init];
UINavigationItem *navItem = [[[UINavigationItem alloc] initWithTitle:@"ModalViewControllerTest"] autorelease];
UIBarButtonItem *done = [[[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemDone target:self action:@selector(dismissView:)] autorelease];
navItem.rightBarButtonItem = done;
navBar.items = [NSArray arrayWithObject:navItem];
[self.view addSubview:navBar];
}

Answer 1

UIBarButtonItem *infoItem = [[UIBarButtonItem alloc] 
                          initWithTitle:@"Info" 
                          style:UIBarButtonItemStyleBordered 
                          target:nil 
                          action:@selector(Infobuttonpressed)];

应该是

UIBarButtonItem *infoItem = [[UIBarButtonItem alloc] 
                          initWithTitle:@"Info" 
                          style:UIBarButtonItemStyleBordered 
                          target:self
                          action:@selector(Infobuttonpressed:)];

发现差异？首先，您错过了一个目标（应该是self，而不是nil）。其次，选择器末尾的冒号是签名的一部分，你错过了它，所以它没有调用你的方法（InfoButtonPressed:(id)sender）。

顺便说一下，方法应该以小写名称开头。

Answer 2

你不需要pushModalViewController和pushViewController

假设您的视图已经在UINavigationController的实例中被控制，pushModalViewController本身就可以工作。

编辑 - 删除对pushViewController的引用。它现在有效吗？

-(void) Infobuttonpressed: (id) sender; 
{ Infoviewcontroller *myView = [[Infoviewcontroller alloc] init]; 
UINavigationController *navController = [[UINavigationController alloc] initWithRootViewController:myView];
UIViewController *pushController = [[UIViewController alloc] init];
[self addSubview:pushController.view];
[pushController presentModalViewController:navController animated:YES];
[myView release]; 
}

Answer 3

infoItem的目标设置为nil。您应该将其设置为定义Infobuttonpressed的类的实例。我假设那是mainviewController？

此外，要调用的选择器指定为：@selector（Infobuttonpressed），而该方法称为“Infobuttonpressed：”，即带有参数。一旦修复目标，这可能会导致运行时错误。

然后，你处理事物的方式有一些特点。正如Nik已经回答的那样，您需要选择是否要以模态方式呈现视图（使用presentModalViewController），或者将其作为导航堆栈的一部分呈现（使用pushViewController），您不能同时执行这两种操作。

如果您将其作为导航堆栈的一部分展示，那么它已经有一个导航栏，因此您不应该自己添加一个导航栏。只需设置self.navigationItem的属性。

有关详细信息，请查看View Controller Programming Guide。

以编程方式在UIToolbar上按下时，为Info按钮显示Modalviewcontroller

3 个答案: