问题
I have been trying to parse an XML file in order to get articles from a website using background fetch.
The link to the tutorial is here.
I've successfully completed the tutorial and parsed my XML file, but instead of pushing the link externally through safari, when the user clicks on the article I would like them to see it in a UIWebView.
How would I implement this in my code?
My CODE:
NewsViewController.h (This file loads a uitableview that runs the background fetch to get the articles):
#import <UIKit/UIKit.h>
@interface NewsViewController : UIViewController<UITableViewDelegate, UITableViewDataSource>
@property (weak, nonatomic) IBOutlet UITableView *tblNews;
- (IBAction)removeDataFile:(id)sender;
-(void)fetchNewDataWithCompletionHandler:(void (^)(UIBackgroundFetchResult))completionHandler;
@end
NewsViewController.m:
#import "NewsViewController.h"
#define NewsFeed @"http://www.teamfortress.com/rss.xml"
#import "XMLParser.h"
@interface NewsViewController ()
@property (nonatomic, strong) UIRefreshControl *refreshControl;
@property (nonatomic, strong) NSArray *arrNewsData;
@property (nonatomic, strong) NSString *dataFilePath;
-(void)refreshData;
-(void)performNewFetchedDataActionsWithDataArray:(NSArray *)dataArray;
@end
@implementation NewsViewController
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
}
return self;
}
- (void)viewDidLoad
{
[super viewDidLoad];
// 1. Make self the delegate and datasource of the table view.
[self.tblNews setDelegate:self];
[self.tblNews setDataSource:self];
// 2. Specify the data storage file path.
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *docDirectory = [paths objectAtIndex:0];
self.dataFilePath = [docDirectory stringByAppendingPathComponent:@"newsdata"];
// 3. Initialize the refresh control.
self.refreshControl = [[UIRefreshControl alloc] init];
[self.refreshControl addTarget:self
action:@selector(refreshData)
forControlEvents:UIControlEventValueChanged];
[self.tblNews addSubview:self.refreshControl];
// 4. Load any saved data.
if ([[NSFileManager defaultManager] fileExistsAtPath:self.dataFilePath]) {
self.arrNewsData = [[NSMutableArray alloc] initWithContentsOfFile:self.dataFilePath];
[self.tblNews reloadData];
}
}
- (IBAction)removeDataFile:(id)sender {
if ([[NSFileManager defaultManager] fileExistsAtPath:self.dataFilePath]) {
[[NSFileManager defaultManager] removeItemAtPath:self.dataFilePath error:nil];
self.arrNewsData = nil;
[self.tblNews reloadData];
}
}
-(void)refreshData{
XMLParser *xmlParser = [[XMLParser alloc] initWithXMLURLString:NewsFeed];
[xmlParser startParsingWithCompletionHandler:^(BOOL success, NSArray *dataArray, NSError *error) {
if (success) {
[self performNewFetchedDataActionsWithDataArray:dataArray];
[self.refreshControl endRefreshing];
}
else{
NSLog(@"%@", [error localizedDescription]);
}
}];
}
-(void)performNewFetchedDataActionsWithDataArray:(NSArray *)dataArray{
// 1. Initialize the arrNewsData array with the parsed data array.
if (self.arrNewsData != nil) {
self.arrNewsData = nil;
}
self.arrNewsData = [[NSArray alloc] initWithArray:dataArray];
// 2. Reload the table view.
[self.tblNews reloadData];
// 3. Save the data permanently to file.
if (![self.arrNewsData writeToFile:self.dataFilePath atomically:YES]) {
NSLog(@"Couldn't save data.");
}
}
-(NSInteger)numberOfSectionsInTableView:(UITableView *)tableView{
return 1;
}
-(NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{
return self.arrNewsData.count;
}
-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"idCellNewsTitle"];
if (cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:@"idCellNewsTitle"];
}
NSDictionary *dict = [self.arrNewsData objectAtIndex:indexPath.row];
cell.textLabel.text = [dict objectForKey:@"title"];
cell.detailTextLabel.text = [dict objectForKey:@"pubDate"];
return cell;
}
-(CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath{
return 80.0;
}
//THIS IS THE SECTION OF CODE THAT OPENS THE LINKS
-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath{
NSDictionary *dict = [self.arrNewsData objectAtIndex:indexPath.row];
NSString *newsLink = [dict objectForKey:@"link"];
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:newsLink]];
}
//END OF THE SECTION
-(void)fetchNewDataWithCompletionHandler:(void (^)(UIBackgroundFetchResult))completionHandler{
XMLParser *xmlParser = [[XMLParser alloc] initWithXMLURLString:NewsFeed];
[xmlParser startParsingWithCompletionHandler:^(BOOL success, NSArray *dataArray, NSError *error) {
if (success) {
NSDictionary *latestDataDict = [dataArray objectAtIndex:0];
NSString *latestTitle = [latestDataDict objectForKey:@"title"];
NSDictionary *existingDataDict = [self.arrNewsData objectAtIndex:0];
NSString *existingTitle = [existingDataDict objectForKey:@"title"];
if ([latestTitle isEqualToString:existingTitle]) {
completionHandler(UIBackgroundFetchResultNoData);
NSLog(@"No new data found.");
}
else{
[self performNewFetchedDataActionsWithDataArray:dataArray];
completionHandler(UIBackgroundFetchResultNewData);
NSLog(@"New data was fetched.");
}
}
else{
completionHandler(UIBackgroundFetchResultFailed);
NSLog(@"Failed to fetch new data.");
}
}];
}
@end
XMLParser.h (This file parses the XML to get the title, date it was published, link, etc.)
#import <Foundation/Foundation.h>
@interface XMLParser : NSObject <NSXMLParserDelegate>
-(id)initWithXMLURLString:(NSString *)xmlUrlString;
-(void)startParsingWithCompletionHandler:(void(^)(BOOL success, NSArray *dataArray, NSError *error))completionHandler;
@end
XMLParser.m:
#import "XMLParser.h"
@interface XMLParser()
@property (nonatomic, strong) NSXMLParser *xmlParser;
@property (nonatomic, strong) NSOperationQueue *operationQueue;
@property (nonatomic, strong) NSMutableArray *arrParsedData;
@property (nonatomic, strong) NSString *currentElement;
@property (nonatomic, strong) NSString *newsTitle;
@property (nonatomic, strong) NSString *newsPubDate;
@property (nonatomic, strong) NSString *newsLink;
@property (nonatomic, strong) void (^completionHandler)(BOOL, NSArray *, NSError *);
@property (nonatomic) BOOL isNewsItem;
@property (nonatomic) BOOL allowedData;
-(void)parse;
-(void)endParsingWithError:(NSError *)error;
@end
@implementation XMLParser
-(id)initWithXMLURLString:(NSString *)xmlUrlString{
self = [super init];
if (self) {
self.xmlParser = [[NSXMLParser alloc] initWithContentsOfURL:[NSURL URLWithString:xmlUrlString]];
self.xmlParser.delegate = self;
self.operationQueue = [NSOperationQueue new];
self.currentElement = @"";
self.isNewsItem = NO;
self.allowedData = NO;
}
return self;
}
#pragma mark - Public method implementation
-(void)startParsingWithCompletionHandler:(void (^)(BOOL, NSArray *, NSError *))completionHandler{
self.completionHandler = completionHandler;
NSInvocationOperation *operation = [[NSInvocationOperation alloc] initWithTarget:self
selector:@selector(parse)
object:nil];
[self.operationQueue addOperation:operation];
}
#pragma mark - Private method implementation
-(void)parse{
if (self.xmlParser != nil) {
[self.xmlParser parse];
}
}
-(void)endParsingWithError:(NSError *)error{
BOOL success = (error == nil) ? YES : NO;
self.completionHandler(success, self.arrParsedData, error);
}
#pragma mark - NSXMLParserDelegate method implementation
-(void)parserDidStartDocument:(NSXMLParser *)parser{
if (self.arrParsedData != nil) {
[self.arrParsedData removeAllObjects];
self.arrParsedData = nil;
}
self.arrParsedData = [[NSMutableArray alloc] init];
}
-(void)parserDidEndDocument:(NSXMLParser *)parser{
[self performSelectorOnMainThread:@selector(endParsingWithError:) withObject:nil waitUntilDone:NO];
}
-(void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict{
if ([elementName isEqualToString:@"item"]) {
self.isNewsItem = YES;
}
if (self.isNewsItem) {
if ([elementName isEqualToString:@"title"] ||
[elementName isEqualToString:@"pubDate"] ||
[elementName isEqualToString:@"link"]) {
self.allowedData = YES;
}
}
self.currentElement = elementName;
}
-(void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName{
if ([elementName isEqualToString:@"item"]) {
self.isNewsItem = NO;
NSDictionary *dict = @{@"title": self.newsTitle,
@"pubDate": self.newsPubDate,
@"link": self.newsLink
};
[self.arrParsedData addObject:dict];
}
if (self.isNewsItem) {
if ([elementName isEqualToString:@"title"] ||
[elementName isEqualToString:@"pubDate"] ||
[elementName isEqualToString:@"link"]) {
self.allowedData = NO;
}
}
}
-(void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string{
if (self.allowedData) {
if ([self.currentElement isEqualToString:@"title"]) {
self.newsTitle = string;
}
else if ([self.currentElement isEqualToString:@"pubDate"]){
self.newsPubDate = string;
}
else if ([self.currentElement isEqualToString:@"link"]){
self.newsLink = string;
}
}
}
-(void)parser:(NSXMLParser *)parser parseErrorOccurred:(NSError *)parseError{
[self performSelectorOnMainThread:@selector(endParsingWithError:) withObject:parseError waitUntilDone:NO];
}
-(void)parser:(NSXMLParser *)parser validationErrorOccurred:(NSError *)validationError{
[self performSelectorOnMainThread:@selector(endParsingWithError:) withObject:validationError waitUntilDone:NO];
}
@end
If you would like to run the project yourself, you can find it on Github here
NOTE When using the link, the Xcode project is under "Your Guide to TF2".
Thanks to anyone that helps!
回答1:
Add a UIViewController, include a UIWebView. Change your didSelectRowAtIndexPath
- (void)tableView:(UITableView *)tableView didDeselectRowAtIndexPath:(NSIndexPath *)indexPath{
}
- (void) prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender{
if([segue.identifier isEqualToString:@"detail"]){
DetailViewController *detail = segue.destinationViewController;
NSIndexPath *indexPath = [self.tblNews indexPathForSelectedRow];
detail.item = [self.arrNewsData objectAtIndex:indexPath.row];
}
}
In your Detailview header file:
#import <UIKit/UIKit.h>
@interface DetailViewController : UIViewController<UIWebViewDelegate> {
NSDictionary *item;
}
@property (retain, nonatomic) NSDictionary *item;
@property (retain, nonatomic) IBOutlet UIWebView *itemSummary;
@end
In your implementation:
#import "DetailViewController.h"
@interface DetailViewController ()
@end
@implementation DetailViewController
@synthesize item;
@synthesize itemSummary = _itemSummary;
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
}
return self;
}
- (void)viewDidLoad
{
[super viewDidLoad];
_itemSummary.delegate = self;
_itemSummary.scalesPageToFit = YES;
NSURL* url = [NSURL URLWithString:[item objectForKey:@"link"]];
[_itemSummary loadRequest:[NSURLRequest requestWithURL:url]];
// Do any additional setup after loading the view.
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
/*
#pragma mark - Navigation
// In a storyboard-based application, you will often want to do a little preparation before navigation
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
// Get the new view controller using [segue destinationViewController].
// Pass the selected object to the new view controller.
}
*/
@end
Add an NSMutableDictionary and NSMutableStrring to your parser header:
@interface XMLParser : NSObject <NSXMLParserDelegate> {
NSMutableDictionary *item;
NSMutableString * currentLink;
}
@property (retain, nonatomic) NSMutableString *currentLink;
In your implementation:
Within your didStartElement:
if ([elementName isEqualToString:@"item"]) {
item = [[NSMutableDictionary alloc] init];
self.currentLink = [[NSMutableString alloc] init];
self.isNewsItem = YES;
}
in your didEndElement:
if ([elementName isEqualToString:@"item"]) {
self.isNewsItem = NO;
[item setObject:self.currentLink forKey:@"link"];
in your foundCharacters:
else if ([self.currentElement isEqualToString:@"link"]){
self.newsLink = string;
[self.currentLink appendString:string];
}
In your storyboard: Embed your tableviewcontroller in a nav controller, add a push segue from your tableview to the detail view, add the identifier of "detail".
Also committed the changes to your git.
来源：https://stackoverflow.com/questions/22888880/parsing-links-from-xml-file-and-pushing-it-to-a-uiwebview