另一个UIViewController中的UIViewController的新实例:为什么不能设置实例变量? [英] New instance of a UIViewController within another UIViewController: Why can't I set an instance variable?
问题描述
因此，我有一个名为MyTabBarViewController的UIViewController子类，该子类具有UIScrollView.在MyTabBarViewController内部，我正在创建另一个名为PhotoViewController的UIViewController子类的实例. (注意:我正在这样做，所以我可以使用IB设置IBOutlets)
我正在尝试从我的TabBarViewController设置每个PhotoViewController实例的标签.然后，我为每个PhotoViewController初始化了笔尖，因此给人的印象是，每个PhotoViewController实例都将连接到其各自的IBOutlets-使我可以使用pvc.label.text = @我想要的文本"来简单地设置标签名称. /p>
您能解释一下为什么我的逻辑不正确吗?因为它不起作用并且不确定要怎么做. :-/
MyTabBarViewController.m
#import "MyTabBarViewController.h"
@implementation MyTabBarViewController
@synthesize pageControl,scroller;
-(IBAction)clickPageControl:(id)sender
{
int page=pageControl.currentPage;
CGRect frame=scroller.frame;
frame.origin.x = frame.size.width * page;
frame.origin.y = 0;
[scroller scrollRectToVisible:frame animated:YES];
}
-(void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
int page = scrollView.contentOffset.x/scrollView.frame.size.width;
pageControl.currentPage=page;
}
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
}
return self;
}
- (void)dealloc
{
[super dealloc];
}
- (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.
}
#pragma mark - View lifecycle
- (void)viewDidLoad
{
[super viewDidLoad];
scroller.delegate=self;
scroller.pagingEnabled=YES;
scroller.directionalLockEnabled=YES;
scroller.showsHorizontalScrollIndicator=NO;
scroller.showsVerticalScrollIndicator=NO;
scroller.contentSize=CGSizeMake(pageControl.numberOfPages*scroller.frame.size.width, scroller.frame.size.height);
CGFloat scrollWidth = 0;
int pageNumber = 0;
for (int i=0; i<3; i++)
{
PhotoViewController *pvc = [[PhotoViewController alloc] initWithNibName:@"PhotoViewController" bundle:nil];
CGRect rect = scroller.frame;
rect.size.height = scroller.frame.size.height;
rect.size.width = scroller.frame.size.width;
rect.origin.x = scroller.frame.origin.x + scrollWidth;
rect.origin.y = scroller.frame.origin.y;
pvc.label.text = [NSString stringWithFormat:@"%d", pageNumber];
pvc.label.textColor = [UIColor redColor];
pvc.view.frame = rect;
[scroller addSubview:pvc.view];
[pvc release];
pageNumber++;
scrollWidth += scroller.frame.size.width;
}
pageControl.numberOfPages=3;
pageControl.currentPage=0;
[self.view addSubview:scroller];
}
- (void)viewDidUnload
{
[super viewDidUnload];
// Release any retained subviews of the main view.
// e.g. self.myOutlet = nil;
}
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
// Return YES for supported orientations
return (interfaceOrientation == UIInterfaceOrientationPortrait);
}
@end
PhotoViewController.h非常简单.而且PhotoViewController.m也是，但是如果我的问题在那里，我已经包含了实现文件.
PhotoViewController.m
#import "PhotoViewController.h"
@implementation PhotoViewController
@synthesize label, imageView, sendButton, cancelButton;
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
}
return self;
}
- (void)dealloc
{
[super dealloc];
}
- (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.
}
#pragma mark - View lifecycle
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view from its nib.
}
- (void)viewDidUnload
{
[super viewDidUnload];
// Release any retained subviews of the main view.
// e.g. self.myOutlet = nil;
}
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
// Return YES for supported orientations
return (interfaceOrientation == UIInterfaceOrientationPortrait);
}
@end
您不能像这样设置任何与视图相关的值(创建对象并从该视图中设置其他输入项).
因为不能在任何视图控制器的viewDidLoad之前设置任何级别的值.需要的是，需要相应地设置标签的字符串类型的属性，并在MyTabBarViewController中设置其值，然后从堆栈中拾取对象在PhotoViewController中的MyTabBarViewController类中，然后访问它的属性并设置标签.
要从堆栈中选择视图对象，您需要使用此行
MyTabBarViewController *obj = (MyTabBarViewController *)[self.navigationController.viewControllers objectAtIndex: [self.navigationController.viewControllers count]-2];
So I have a UIViewController subclass called MyTabBarViewController that has a UIScrollView. Inside of MyTabBarViewController I'm creating an instance of another UIViewController subclass called PhotoViewController. (Note: I'm doing this so I can set up the IBOutlets using IB)
I'm trying to set the label of each PhotoViewController instance from my TabBarViewController. And I init with nib for each PhotoViewController so I was under the impression that each PhotoViewController instance would be wired up to their respective IBOutlets - allowing me to simply set the label name using pvc.label.text = @"text I want".
Could you explain why my logic is incorrect? Because it's not working and not really sure what to do. :-/
MyTabBarViewController.m
#import "MyTabBarViewController.h"
@implementation MyTabBarViewController
@synthesize pageControl,scroller;
-(IBAction)clickPageControl:(id)sender
{
int page=pageControl.currentPage;
CGRect frame=scroller.frame;
frame.origin.x = frame.size.width * page;
frame.origin.y = 0;
[scroller scrollRectToVisible:frame animated:YES];
}
-(void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
int page = scrollView.contentOffset.x/scrollView.frame.size.width;
pageControl.currentPage=page;
}
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
}
return self;
}
- (void)dealloc
{
[super dealloc];
}
- (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.
}
#pragma mark - View lifecycle
- (void)viewDidLoad
{
[super viewDidLoad];
scroller.delegate=self;
scroller.pagingEnabled=YES;
scroller.directionalLockEnabled=YES;
scroller.showsHorizontalScrollIndicator=NO;
scroller.showsVerticalScrollIndicator=NO;
scroller.contentSize=CGSizeMake(pageControl.numberOfPages*scroller.frame.size.width, scroller.frame.size.height);
CGFloat scrollWidth = 0;
int pageNumber = 0;
for (int i=0; i<3; i++)
{
PhotoViewController *pvc = [[PhotoViewController alloc] initWithNibName:@"PhotoViewController" bundle:nil];
CGRect rect = scroller.frame;
rect.size.height = scroller.frame.size.height;
rect.size.width = scroller.frame.size.width;
rect.origin.x = scroller.frame.origin.x + scrollWidth;
rect.origin.y = scroller.frame.origin.y;
pvc.label.text = [NSString stringWithFormat:@"%d", pageNumber];
pvc.label.textColor = [UIColor redColor];
pvc.view.frame = rect;
[scroller addSubview:pvc.view];
[pvc release];
pageNumber++;
scrollWidth += scroller.frame.size.width;
}
pageControl.numberOfPages=3;
pageControl.currentPage=0;
[self.view addSubview:scroller];
}
- (void)viewDidUnload
{
[super viewDidUnload];
// Release any retained subviews of the main view.
// e.g. self.myOutlet = nil;
}
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
// Return YES for supported orientations
return (interfaceOrientation == UIInterfaceOrientationPortrait);
}
@end
PhotoViewController.h is pretty straight-forward. And PhotoViewController.m is too but I've included the implementation file in the event that my problem is in there.
PhotoViewController.m
#import "PhotoViewController.h"
@implementation PhotoViewController
@synthesize label, imageView, sendButton, cancelButton;
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
}
return self;
}
- (void)dealloc
{
[super dealloc];
}
- (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.
}
#pragma mark - View lifecycle
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view from its nib.
}
- (void)viewDidUnload
{
[super viewDidUnload];
// Release any retained subviews of the main view.
// e.g. self.myOutlet = nil;
}
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
// Return YES for supported orientations
return (interfaceOrientation == UIInterfaceOrientationPortrait);
}
@end
You cant set any view related values like this(making object and set other enteries from that view).
Because you can't set any level's value before viewDidLoad of any view controller.What you need, you need set properties of string type for labels accordingly and set their values in MyTabBarViewController then from the stack pick up the object of the MyTabBarViewController class in PhotoViewController and then access it's properties and set your labels.
For picking the view object from stack you need to use this line
MyTabBarViewController *obj = (MyTabBarViewController *)[self.navigationController.viewControllers objectAtIndex: [self.navigationController.viewControllers count]-2];
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