新的 iOS 开发人员为 iPhone 编写了第一个委托应用程序。
模态称为父视图控制器有六个子视图，它们使用父视图中的分段控件进行转换。我收到错误消息：
子视图控制器和调用时必须有一个共同的父视图控制器 -[UIViewController transitionFromViewController:toViewController:duration:options:animations:completion:]
当我按下第二个按钮时，即我可以在父母出现后按下任何按钮并且它可以工作。但是下次我按下一个新按钮时，我得到了上面的崩溃。使用 NSLogs 我已经确定崩溃的原因是当前和新的孩子在按钮按下之间都失去了他们的父母。我不知道为什么。父级的相关代码如下：
接口代码：
#import <UIKit/UIKit.h>
#import "WorksheetScrollViewController.h"
#import "Worksheet1ViewController.h"
#import "Worksheet2ViewController.h"
#import "Worksheet3ViewController.h"
#import "Worksheet4ViewController.h"
#import "WorksheetEndViewController.h"
@interface WorkSheetParentViewController : UIViewController
{
IBOutlet UISegmentedControl *segControl;
IBOutlet UIBarButtonItem *doneButton;
IBOutlet UIView *childContainerView;
WorksheetScrollViewController *wStart;
Worksheet1ViewController *w1;
Worksheet2ViewController *w2;
Worksheet3ViewController *w3;
Worksheet4ViewController *w4;
WorksheetEndViewController *wEnd;
UIViewController *currentVC;
UIViewController *newVC;
}
-(void)initToolbar;
-(IBAction) doneButtonPressed:(id)sender;
-(IBAction) segControlChanged:(id)sender;
-(void)swapViewControllers;
实现代码：
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view from its nib.
wStart = [[WorksheetScrollViewController alloc ]initWithNibName:@"WorksheetScrollViewController" bundle:nil];
[self addChildViewController:wStart];
wStart.view.frame=childContainerView.bounds;
[childContainerView addSubview:wStart.view];
[wStart didMoveToParentViewController:self];
currentVC = wStart;
}
- (IBAction) segControlChanged:(id)sender
{
NSLog(@"selected tab bar item:%i",segControl.selectedSegmentIndex);
switch (segControl.selectedSegmentIndex) {
case 0:
if (!wStart) {
wStart = [[WorksheetScrollViewController alloc ]initWithNibName:@"WorksheetScrollViewController" bundle:nil];
}
newVC = wStart;
break;
case 1:
if (!w1) {
w1 = [[Worksheet1ViewController alloc ]initWithNibName:@"Worksheet1ViewController" bundle:nil];
}
newVC = w1;
break;
case 2:
if (!w2) {
w2 = [[Worksheet2ViewController alloc ]initWithNibName:@"Worksheet2ViewController" bundle:nil];
}
newVC = w2;
break;
case 3:
if (!w3) {
w3 = [[Worksheet3ViewController alloc ]initWithNibName:@"Worksheet3ViewController" bundle:nil];
}
newVC = w3;
break;
case 4:
if (!w4) {
w4 = [[Worksheet4ViewController alloc ]initWithNibName:@"Worksheet4ViewController" bundle:nil];
}
newVC = w4;
break;
case 5:
if (!wEnd) {
wEnd = [[WorksheetEndViewController alloc ]initWithNibName:@"WorksheetEndViewController" bundle:nil];
}
newVC = wEnd;
break;
default:
break;
}
[self swapViewControllers];
}
-(void)swapViewControllers
{
NSLog(@"top current VC parent = %@",currentVC.parentViewController);
NSLog(@"top new VC parent = %@",newVC.parentViewController);
[currentVC willMoveToParentViewController:nil];
newVC.view.frame=childContainerView.bounds;
[self addChildViewController:newVC];
NSLog(@"current VC parent = %@",currentVC.parentViewController);
NSLog(@"new VC parent = %@",newVC.parentViewController);
[self transitionFromViewController:currentVC
toViewController:newVC
duration:1.0
options:UIViewAnimationOptionTransitionCurlUp
animations:nil
completion:^(BOOL finished) {
[currentVC removeFromParentViewController];
[newVC didMoveToParentViewController:self];
}];
currentVC = newVC;
NSLog(@"bottom current VC parent = %@",currentVC.parentViewController);
NSLog(@"bottom new VC parent = %@",newVC.parentViewController);
}
按按钮 1，然后按按钮 2 的 Nslog 结果：
2013-08-26 14:49:07.245 Alveolar Gas iPhone[556:707] selected tab bar item:1
2013-08-26 14:49:07.251 Alveolar Gas iPhone[556:707] top current VC parent = <WorkSheetParentViewController: 0x198da0>
2013-08-26 14:49:07.256 Alveolar Gas iPhone[556:707] top new VC parent = (null)
2013-08-26 14:49:07.437 Alveolar Gas iPhone[556:707] current VC parent = <WorkSheetParentViewController: 0x198da0>
2013-08-26 14:49:07.440 Alveolar Gas iPhone[556:707] new VC parent = <WorkSheetParentViewController: 0x198da0>
2013-08-26 14:49:07.460 Alveolar Gas iPhone[556:707] bottom current VC parent = <WorkSheetParentViewController: 0x198da0>
2013-08-26 14:49:07.462 Alveolar Gas iPhone[556:707] bottom new VC parent = <WorkSheetParentViewController: 0x198da0>
2013-08-26 14:49:13.984 Alveolar Gas iPhone[556:707] selected tab bar item:2
2013-08-26 14:49:33.912 Alveolar Gas iPhone[556:707] top current VC parent = (null)
2013-08-26 14:49:50.038 Alveolar Gas iPhone[556:707] top new VC parent = (null)
2013-08-26 14:55:36.149 Alveolar Gas iPhone[556:707] current VC parent = (null)
2013-08-26 14:55:36.153 Alveolar Gas iPhone[556:707] new VC parent = <WorkSheetParentViewController: 0x198da0>
2013-08-26 14:55:36.160 Alveolar Gas iPhone[556:707] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Children view controllers <Worksheet1ViewController: 0x1ea780> and <Worksheet2ViewController: 0x1403b0> must have a common parent view controller when calling -[UIViewController transitionFromViewController:toViewController:duration:options:animations:completion:]'