问题
I have set up an NSScanner to work on the tap of a UIButton with the following code:
-(IBAction)doLoadTTData
{
NSString *Period1String = [NSString stringWithContentsOfFile:[[NSBundle mainBundle] pathForResource: @"Period1String" ofType: @"txt"] usedEncoding:nil error:nil];
NSString *Period2String = [NSString stringWithContentsOfFile:[[NSBundle mainBundle] pathForResource: @"Period2String" ofType: @"txt"] usedEncoding:nil error:nil];
NSString *Period3String = [NSString stringWithContentsOfFile:[[NSBundle mainBundle] pathForResource: @"Period3String" ofType: @"txt"] usedEncoding:nil error:nil];
NSString *Period4String = [NSString stringWithContentsOfFile:[[NSBundle mainBundle] pathForResource: @"Period4String" ofType: @"txt"] usedEncoding:nil error:nil];
NSString *Period5String = [NSString stringWithContentsOfFile:[[NSBundle mainBundle] pathForResource: @"Period5String" ofType: @"txt"] usedEncoding:nil error:nil];
NSURL *currentURL = [NSURL URLWithString:webView.request.URL.absoluteString];
NSLog(@"Loaded Timetable");
NSError *loaderror;
NSString *page = [NSString stringWithContentsOfURL:currentURL
encoding:NSASCIIStringEncoding
error:&loaderror];
[webView loadHTMLString:page baseURL:currentURL];
NSString *Period1Data = nil;
NSScanner *htmlScanner = [NSScanner scannerWithString:page];
[htmlScanner scanUpToString:Period1String intoString:NULL];
[htmlScanner scanString:Period1String intoString:NULL];
[htmlScanner scanUpToString:@"</FONT>" intoString:&Period1Data];
NSLog(@"Collected Period 1 Data: %@", Period1Data);
if(Period1Data == NULL)
{
Period1Data = @"Not Available";
[period1label setText:@"Not Available"];
}
else if(Period1Data == @"(null)")
{
Period1Data = @"Not Available";
[period1label setText:@"Not Available"];
}
else
{
[period1label setText:Period1Data];
}
NSString *Period2Data = nil;
[htmlScanner scanUpToString:Period2String intoString:NULL];
[htmlScanner scanString:Period2String intoString:NULL];
[htmlScanner scanUpToString:@"</FONT>" intoString:&Period2Data];
if(Period2Data == NULL)
{
Period2Data = @"Not Available";
[period2label setText:@"Not Available"];
}
else if(Period2Data == @"(null)")
{
Period2Data = @"Not Available";
[period2label setText:@"Not Available"];
}
else
{
[period2label setText:Period2Data];
[period2label setText:@"Not Available"];
}
NSLog(@"Collected Period 2 Data: %@", Period2Data);
NSString *Period3Data = nil;
[htmlScanner scanUpToString:Period3String intoString:NULL];
[htmlScanner scanString:Period3String intoString:NULL];
[htmlScanner scanUpToString:@"</FONT>" intoString:&Period3Data];
if(Period3Data == NULL)
{
Period3Data = @"Not Available";
[period3label setText:@"Not Available"];
}
else if(Period3Data == @"(null)")
{
Period3Data = @"Not Available";
[period3label setText:@"Not Available"];
}
else
{
[period3label setText:Period3Data];
}
NSLog(@"Collected Period 3 Data: %@", Period3Data);
NSString *Period4Data = nil;
[htmlScanner scanUpToString:Period4String intoString:NULL];
[htmlScanner scanString:Period4String intoString:NULL];
[htmlScanner scanUpToString:@"</FONT>" intoString:&Period4Data];
if(Period4Data == NULL)
{
Period4Data = @"Not Available";
[period4label setText:@"Not Available"];
}
else if(Period4Data == @"(null)")
{
Period4Data = @"Not Available";
[period4label setText:@"Not Available"];
}
else
{
[period4label setText:Period4Data];
}
NSLog(@"Collected Period 4 Data: %@", Period4Data);
NSString *Period5Data = nil;
[htmlScanner scanUpToString:Period5String intoString:NULL];
[htmlScanner scanString:Period5String intoString:NULL];
[htmlScanner scanUpToString:@"</FONT>" intoString:&Period5Data];
if(Period5Data == NULL)
{
Period5Data = @"Not Available";
[period5label setText:@"Not Available"];
}
else if(Period5Data == @"(null)")
{
Period5Data = @"Not Available";
[period5label setText:@"Not Available"];
}
else
{
[period5label setText:Period5Data];
}
NSLog(@"Collected Period 5 Data: %@", Period5Data);
NSString* TimetableDate = nil;
NSString *DateString = [NSString stringWithFormat:@"<FONT size=2> <STRONG><FONT size=3>"];
[htmlScanner scanUpToString:DateString intoString:NULL];
[htmlScanner scanString:DateString intoString:NULL];
[htmlScanner scanUpToString:@"</FONT>" intoString:&TimetableDate];
NSString *timetablefulldate = [NSString stringWithFormat:@"Timetable for %@", TimetableDate];
[timetabledate setText:timetablefulldate];
[TimetableLoading setHidden:YES];
[TimetableLoadingBG setHidden:YES];
if(Period1Data == NULL && Period2Data == NULL && Period3Data == NULL && Period4Data == NULL && Period5Data == NULL)
{
if(ttbacking.tag == 10)
{
NSLog(@"Already showing message");
}
else
{
UIAlertView *message = [[UIAlertView alloc] initWithTitle:@"Timetable"
message:@"Looks like you don't have any lessons today! Maybe you'd like to get some homework out of the way?"
delegate:nil
cancelButtonTitle:@"I'll have a think"
otherButtonTitles:nil];
[message show];
[ttbacking setTag:10];
}
[period1label setText:@"Free Time"];
[period2label setText:@"Free Time"];
[period3label setText:@"Free Time"];
[period4label setText:@"Free Time"];
[period5label setText:@"Free Time"];
period1backing.image = [UIImage imageNamed:@"redperiodbacking.png"];
period2backing.image = [UIImage imageNamed:@"redperiodbacking.png"];
period3backing.image = [UIImage imageNamed:@"redperiodbacking.png"];
period4backing.image = [UIImage imageNamed:@"redperiodbacking.png"];
period5backing.image = [UIImage imageNamed:@"redperiodbacking.png"];
}
if(TimetableDate == NULL)
{
[timetabledate setText:@"No timetable today"];
}
[prevDay setHidden:NO];
[nextDay setHidden:NO];
NSLog(@"Student Timetable collected and published");
}
Unfortunately, this only works with WiFi and not 3G.
If I press the button on a 3G connection, all the labels show "Not Available" because the results are "NULL". This is weird because I put the UIWebView in front of everything one time to test if the page actually loaded and it did, just as if it were on WiFi. For some reason the NSScanner isn't working on 3G.
Why could this be? Just tell me if there is any other code you need to see...
回答1:
I have a couple things to say. First of all, what you're doing with scanners and stuff is really quite hacky. If you're trying to parse HTML, you should be doing it the right way. Use something like libxml2 (which comes built into the iPhone), to actually parse the html and get stuff from it. Quite honestly your system could break with a small update or malfunction with the page.
Enough with the ranting, but if you decide to leave your current system in place, you could try retrieving the actual html from the currently-loaded page.
For example (as I already posted in your other question):
NSString *path = @"document.body.innerHTML";
NSString *html = [webView stringByEvaluatingJavaScriptFromString:path];
Since your web view can load, then you should be able to grab the contents from the loaded webview like so.
And if I may add, this is not going to work: else if(Period1Data == @"(null)"). The debugger prints (null), but if a string is null it's never going to appear as (null). And if you were comparing strings, you would be doing isEqualToString:, but I'm running away with myself. ;)
来源：https://stackoverflow.com/questions/8508311/nsscanner-working-on-wifi-but-not-3g