Iphone 如何从使用NSURLConnection及其';什么是代表课?
我正在尝试将代码从UITableViewController类移动到“helper”类 代码利用NSURLConnection获取和解析JSON,然后填充NSMUTABLEARRY 我想做的是在我的助手类中调用一个返回NSMutableArray的方法。我不明白的是,如何从NSURLConnection的ConnectionIDFinishLoading委托类(实际构建数组的地方)返回数组,就好像它是从启动连接的最初调用的方法返回一样。换句话说,调用NSURLConnection的方法如何获得控制权,以便能够从整个操作返回值 下面是helper类中的相关方法。如何让getMovies方法返回ConnectionDiFinishLoading委托类中构建的listOfMoviesIphone 如何从使用NSURLConnection及其';什么是代表课?,iphone,objective-c,nsurlconnection,Iphone,Objective C,Nsurlconnection,我正在尝试将代码从UITableViewController类移动到“helper”类 代码利用NSURLConnection获取和解析JSON,然后填充NSMUTABLEARRY 我想做的是在我的助手类中调用一个返回NSMutableArray的方法。我不明白的是,如何从NSURLConnection的ConnectionIDFinishLoading委托类(实际构建数组的地方)返回数组,就好像它是从启动连接的最初调用的方法返回一样。换句话说,调用NSURLConnection的方法如何获得控
-(NSMutableArray)getMovies:(NSURL*)url {
responseData = [[NSMutableData data] retain];
NSURLRequest *request = [NSURLRequest requestWithURL:url];
//NSURLRequest* request = [NSURLRequest requestWithURL: url cachePolicy: NSURLRequestUseProtocolCachePolicy timeoutInterval: 30.0];
connection = [[NSURLConnection alloc] initWithRequest:request delegate:self];
}
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {
[responseData setLength:0];
}
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
[responseData appendData:data];
}
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {
//TODO error handling for connection
}
- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
//---initialize the array---
listOfMovies = [[NSMutableArray alloc] init];
tmdbMovies = [[NSArray alloc] init];
posters = [[NSArray alloc] init];
thumbs = [[NSDictionary alloc] init];
NSString *responseString = [[NSString alloc] initWithData:responseData encoding:NSUTF8StringEncoding];
SBJsonParser *json = [[SBJsonParser new] autorelease];
tmdbMovies = [json objectWithString:responseString];
// loop through all the top level elements in JSON
for (id movie in tmdbMovies) {
// 0 - Name
// 1 - Meta
// 2 - Url
if ((NSNull *)[movie objectForKey:@"name"] != [NSNull null]) {
if (![[movie objectForKey:@"name"] isEqualToString:@""]) {
name = [movie objectForKey:@"name"];
}
}
if ((NSNull *)[movie objectForKey:@"info"] != [NSNull null]) {
if (![[movie objectForKey:@"info"] isEqualToString:@""]) {
meta = [movie objectForKey:@"info"];
}
}
if ((NSNull *)[movie objectForKey:@"thumb"] != [NSNull null]) {
if (![[movie objectForKey:@"thumb"] isEqualToString:@""]) {
thumbUrl = [movie objectForKey:@"thumb"];
}
}
NSLog(@"Name: %@", name);
NSLog(@"Info: %@", meta);
NSLog(@"Thumb: %@", thumbUrl);
NSMutableArray *movieData = [[NSMutableArray alloc] initWithObjects:name,meta,thumbUrl,nil];
// add movieData array to listOfJMovies array
[listOfMovies addObject:movieData];
[movieData release];
}
//FIXME: Connection warning
if (connection!=nil) {
[connection release];
}
[responseData release];
[responseString release];
}
如何让getMovies方法返回ConnectionDiFinishLoading委托类中构建的listOfMovies
-(NSMutableArray)getMovies:(NSURL*)url {
responseData = [[NSMutableData data] retain];
NSURLRequest *request = [NSURLRequest requestWithURL:url];
//NSURLRequest* request = [NSURLRequest requestWithURL: url cachePolicy: NSURLRequestUseProtocolCachePolicy timeoutInterval: 30.0];
connection = [[NSURLConnection alloc] initWithRequest:request delegate:self];
}
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {
[responseData setLength:0];
}
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
[responseData appendData:data];
}
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {
//TODO error handling for connection
}
- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
//---initialize the array---
listOfMovies = [[NSMutableArray alloc] init];
tmdbMovies = [[NSArray alloc] init];
posters = [[NSArray alloc] init];
thumbs = [[NSDictionary alloc] init];
NSString *responseString = [[NSString alloc] initWithData:responseData encoding:NSUTF8StringEncoding];
SBJsonParser *json = [[SBJsonParser new] autorelease];
tmdbMovies = [json objectWithString:responseString];
// loop through all the top level elements in JSON
for (id movie in tmdbMovies) {
// 0 - Name
// 1 - Meta
// 2 - Url
if ((NSNull *)[movie objectForKey:@"name"] != [NSNull null]) {
if (![[movie objectForKey:@"name"] isEqualToString:@""]) {
name = [movie objectForKey:@"name"];
}
}
if ((NSNull *)[movie objectForKey:@"info"] != [NSNull null]) {
if (![[movie objectForKey:@"info"] isEqualToString:@""]) {
meta = [movie objectForKey:@"info"];
}
}
if ((NSNull *)[movie objectForKey:@"thumb"] != [NSNull null]) {
if (![[movie objectForKey:@"thumb"] isEqualToString:@""]) {
thumbUrl = [movie objectForKey:@"thumb"];
}
}
NSLog(@"Name: %@", name);
NSLog(@"Info: %@", meta);
NSLog(@"Thumb: %@", thumbUrl);
NSMutableArray *movieData = [[NSMutableArray alloc] initWithObjects:name,meta,thumbUrl,nil];
// add movieData array to listOfJMovies array
[listOfMovies addObject:movieData];
[movieData release];
}
//FIXME: Connection warning
if (connection!=nil) {
[connection release];
}
[responseData release];
[responseString release];
}
我要说的是你不应该那样做
网络请求应异步进行。如果您的getMovies
要发出一个同步请求,并且仅当它有数据时才返回,那么在等待网络连接完成时,您将阻塞整个线程。如果您的主线程正在调用getMovies
,这通常是一个坏主意,也是一个糟糕的主意。阻止主线程将阻止您响应触摸或更新UI,您的应用程序将显示为冻结状态,如果您的用户没有在沮丧中首先退出,操作系统将终止它
相反,当数据可用时(或检索数据失败时),让helper类通过委托回调、通知、KVO或您喜欢的任何机制通知调用方。以下是类似伪代码的步骤:
[helperInstance setDelegate:self];//其中self是UITableViewController类
[helper doSomething:^ (id loaded) {
[modelObject refresh:loaded]; // or whatever you need to do
}];
[代表完成加载数据:JSONData]代码>
@property (nonatomic, assign) id<YourProtocol> delegate;
@属性(非原子,赋值)id委托;
希望这有帮助,
Moszi从根本上说,现在发生的是您正在启动一个异步网络负载(异步是这样做的正确方法,几乎可以肯定),然后您需要某种方法来恢复负载开始之前正在执行的任何操作。您有几个选择:
- 创建自己的代理协议。然后,UITableViewController将自身设置为帮助者的委托,帮助者将调用
或您命名的任何方法。Cocoa编程指南中有关于编写委托的更多信息helperIDLoad
- 使用块和连续传递样式。这是一个有点先进,但我喜欢它。在UITableViewController中,您可以编写如下内容:
然后在助手中写下:[helper doSomething:^ (id loaded) { [modelObject refresh:loaded]; // or whatever you need to do }];
- (void)doSomething:(void ^ (id))continuation { _continuation = continuation; //kick off network load } - (void)connectionDidFinishLoading:(NSURLConnection *)connection { _continuation(_data); }
- 使用通知。阅读NSNotificationCenter文档
- 使用KVO。《KVO编程指南》中有很多关于键值的好信息
@protocol
,为助手类创建一个委托。然后将-(NSMutableArray)getMovies:(NSURL*)url更改为-(void)getMovies:(NSURL*)url
调用助手方法的类需要实现助手方法的委托
然后-(void)connectionIDFinishLoading:(NSURLConnection*)connection
调用委托方法。最好有一个是成功的,一个是失败的
=更新开始=
您还需要在助手文件中定义一个id委托
,调用类在init之后调用-(void)getMovies:(NSURL*)url
之前将其设置为self。这样,助手文件就知道在哪里回叫
getMovies *movieListCall = [[getMovies alloc] init];
movieListCall.delegate = self;
[movieListCall getMovies:<your NSURL goes here>];
在getMovies.m文件中添加:
@protocol getMoviesDelegate
@required
- (void)getMoviesSucceeded:(NSMutableArray *)movieArray;
- (void)getMoviesFailed:(NSString *)failedMessage;
@end
@interface getMovies : NSOBject {
id delegate;
}
@property (nonatomic, assign) id delegate;
@synthesize delegate;
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {
//TODO error handling for connection
if ([delegate respondsToSelector:@selector(getMoviesFailed:)]) {
[delegate getMoviesFailed:[error localizedDescription]];
}
}
- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
//finishes with
if ([delegate respondsToSelector:@selector(getMoviesSucceeded:)]) {
[delegate getMoviesSucceeded:listOfMovies];
}
}
更新调用class.h文件以使用getMoviesDelegate
:
@interface MoviesView : UIViewController <getMoviesDelegate>{
.
.
.
}
这是没有测试,但希望给你一个路线图工作
协议很好,因为您可以创建必需的和可选的委托方法,并且它有助于改进您的助手方法,使其在项目中变得非常可重用。如果您已实现协议,但未实现协议所需的委托方法,编译器也会发出警告。如果您遵循此路径,请确保使用conformsToProtocol:
和respondsToSelector:
使用协议或NSNotificationCenter这看起来是一个不错的方法。我会给它一个机会,然后报告。谢谢大家的输入。我在调用[delegate GetMoviesSuccessed:listOfMovies]时收到一个未声明的代理错误;顺便问一下,有没有办法在评论中发布代码?想发布我的Movies.h文件,看看我是否错误地声明了这些方法。实际上,错误发生在if条件下,如下所示:“委托”未声明(首次在此函数中使用)Sry,我假设助手定义了一个delegat,这是我的错。getMovies需要在.h文件中定义一个id委托。我会更新我的答案。谢谢。现在编译,但我在运行时崩溃在这行:movieListCall.delegate=self;错误为[Movies setDelegate:]:无法识别的选择器已发送到实例。顺便说一句,“Movies”是类名,getMovies是方法名。有什么想法吗?嗨,我知道这是一篇非常古老的帖子,但是,如果有多个连接几乎同时启动,我们如何确定哪个连接产生了哪个结果?非常感谢。