在viewDidLoad之后如何更新UIWebView？

Question

This is my first iOS app, so I am probably missing something very simple. Please be kind. I have been tearing my hair out and I could really use some help.

Overview Of App

Basically, this is a single page application that just loads a UIWebView. I have an external accessory (bluetooth barcode scanner) that I connect and basically what I want to do is when the the app receives a scan, I want to call a method in my ViewController and update the UIWebView accordingly.

What Is Working

I am able to connect the scanner, load the first view, which loads the initial webpage, scan a barcode and call the method in my controller.

My Problem

I can't seem to figure out how to update the UIWebView from the method in my controller. It logs the url string to my debugger area, but never actually updates the webview. I am pretty sure I have some delegation wrong or something with my webview instance. There must be some glue code here that I am missing.

My Code HelloWorldViewController.h

#import <UIKit/UIKit.h>
#import "KScan.h"

@interface HelloWorldViewController : UIViewController <UIWebViewDelegate> { 

  IBOutlet UIWebView *page;
  IBOutlet UILabel *myLabel;

  Boolean IsFirstTime;

  KScan *kscan;

}

- (void)setFirstTime;
- (void)DisplayConnectionStatus; 
- (void)DisplayMessage:(char *)Message; 
- (void)newBarcodeScanned:(NSString *)barcode;
- (void)loadBarcodePage:(NSString *)barcode;

@property (nonatomic, retain) KScan *kscan;
@property (nonatomic, retain) UIWebView *page;
@property (nonatomic, retain) UILabel *myLabel;

@end 

My Code HelloWorldViewController.m

#import "HelloWorldViewController.h"
#import "common.h"

@implementation HelloWorldViewController

@synthesize myLabel;
@synthesize page;
@synthesize kscan;


- (void)setFirstTime
{
    IsFirstTime = true;
}


- (void)viewDidLoad
{
    self.kscan = [[KScan alloc] init];

    [super viewDidLoad];
    page.scrollView.bounces = NO;

    //page.delegate = self;

   [page loadRequest:[NSURLRequest requestWithURL:[NSURL   URLWithString:@"http://192.168.0.187:3000"]]];

}


- (void) newBarcodeScanned:(NSString *)barcode
{
NSLog(@"%s[%@]",__FUNCTION__, barcode);

[self loadBarcodePage:barcode];
} 

- (void)loadBarcodePage:(NSString *)barcode
{
NSLog(@"%s",__FUNCTION__);
NSString *url = [[NSString alloc] initWithFormat:@"http://www.google.com/%@", barcode];
NSLog(@"%@", url);
[page loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:url]]]; 

}

- (void)viewDidUnload
{
    [myLabel release];
    myLabel = nil;
    [super viewDidUnload];
    // Release any retained subviews of the main view.
}

- (BOOL)shouldAutorotateToInterfaceOrientation:   (UIInterfaceOrientation)interfaceOrientation
{
    if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPhone) {
    return (interfaceOrientation != UIInterfaceOrientationPortraitUpsideDown);
    } else {
       return YES;
    }
}

- (void)dealloc {
   [page release];
   [kscan release];
   [myLabel release];
   [super dealloc];
}
@end

Basically, I am just trying to load google.com into my page webview when scanning a barcode. My log statements are being logged with the correct URL, but this line of code doesn't work.

[page loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:url]]];

I am not getting any errors and my xCode debugging skills are not the greatest.

Any help would be greatly appreciated!

Answer 1

It looks like your webview is never allocated, or added to your main view. You are probably talking to a nil instance.

Unless your web view comes from a XIB file (which I doubt since it is not declared as an IBOutlet in your heder file) try adding something like this to your viewDidLoad:

self.page = [[UIWebView alloc] initWithFrame:self.view.bounds];
[self.view addSubview:self.page];