我开发的应用程序是一个与 OS X 服务器通信的 iOS 客户端。这个应用程序的当前版本在主线程上完成了所有的网络逻辑，这对于我想做的事情来说很好。
但是，在下一个版本中，我希望网络逻辑更加灵活。为此，我想专门为其创建一个单独的线程，但我不太确定哪种解决方案适合我的需求。
起初，GCD 看起来是一个不错的候选者，但它似乎只适合在单独的线程上执行大块工作。我想做的是将所有网络逻辑放在一个单独的线程上。iOS 客户端和 OS X 服务器之间的连接是持久的，所有数据流和处理都应该发生在那个单独的线程上。
问题归结为，哪种方法最适合这种情况？
编辑：为了消除任何混淆，我使用的连接使用套接字和 NSStream 实例。我不是在处理连接到远程 Web 服务器的问题。换句话说，AFNetworking 和 ASIHttpRequest 不是我的选择。
您可以使用 runloop（我们称之为 NetworkThread）创建一个线程，运行以下代码：
while (!self.isCancelled) {
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
[[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate distantFuture]];
[pool release];
}
然后您可以使用- (void)performSelector:(SEL)aSelector onThread:(NSThread *)thr withObject:(id)arg waitUntilDone:(BOOL)wait在 NetworkThread 上执行您的网络请求选择器。
所有网络回调将在 NetworkThread 上调用，然后在 NetworkThread 上处理您的响应数据，将最终数据推送到主线程，更新 UI。
AFNetworking 很棒。使用块和 GCD。我编写了一个 NetworkClient 类，它使得调用它变得相当简单。随意使用它或定制它，但我不保证任何东西:)
如果 API 密钥不符合您的需要，可以将其删除。我将它添加为一种为我的所有网络请求增加安全性的方法。我的 Web 服务在返回任何内容之前检查传入的 APIKey 的有效性。
此外，您可以相当灵活地完成您想要的事情。您可以执行同步或异步请求、不警告用户失败的请求等。
基本示例用法：
NSDictionary *params = [NSDictionary dictionaryWithObjectsAndKeys:
@"GetAllParkingLots", @"Command",
nil];
[NetworkClient processURLRequestWithURL:nil andParams:params block:^(id obj) {
// I check to see what kind of object is passed back, in this case I was expecting an Array
if ([obj isKindOfClass:[NSArray class]]) {
// Do something with the Array
[self processNetworkRequestWithArray:(NSArray *)obj];
}
}];
网络客户端.h：
//
// NetworkClient.h
//
// Created by LJ Wilson on 2/18/12.
// Copyright (c) 2012 LJ Wilson All rights reserved.
//
#import <Foundation/Foundation.h>
extern NSString * const APIKey;
@interface NetworkClient : NSObject
+(void)processURLRequestWithURL:(NSString *)url
andParams:(NSDictionary *)params
block:(void (^)(id obj))block;
+(void)processURLRequestWithURL:(NSString *)url
andParams:(NSDictionary *)params
syncRequest:(BOOL)syncRequest
block:(void (^)(id obj))block;
+(void)processURLRequestWithURL:(NSString *)url
andParams:(NSDictionary *)params
syncRequest:(BOOL)syncRequest
alertUserOnFailure:(BOOL)alertUserOnFailure
block:(void (^)(id obj))block;
+(void)handleNetworkErrorWithError:(NSError *)error;
+(void)handleNoAccessWithReason:(NSString *)reason;
@end
网络客户端.m：
//
// NetworkClient.m
//
// Created by LJ Wilson on 2/18/12.
// Copyright (c) 2012 LJ Wilson All rights reserved.
//
#import "NetworkClient.h"
#import "AFHTTPClient.h"
#import "AFHTTPRequestOperation.h"
#import "SBJson.h"
#warning Set APIKey or set to nil
NSString * const APIKey = @"YourAPIKEYGoesHere";
@implementation NetworkClient
+(void)processURLRequestWithURL:(NSString *)url
andParams:(NSDictionary *)params
block:(void (^)(id obj))block {
[self processURLRequestWithURL:url andParams:params syncRequest:NO alertUserOnFailure:NO block:^(id obj) {
block(obj);
}];
}
+(void)processURLRequestWithURL:(NSString *)url
andParams:(NSDictionary *)params
syncRequest:(BOOL)syncRequest
block:(void (^)(id obj))block {
[self processURLRequestWithURL:url andParams:params syncRequest:syncRequest alertUserOnFailure:NO block:^(id obj) {
block(obj);
}];
}
+(void)processURLRequestWithURL:(NSString *)url
andParams:(NSDictionary *)params
syncRequest:(BOOL)syncRequest
alertUserOnFailure:(BOOL)alertUserOnFailure
block:(void (^)(id obj))block {
#warning Fix default url
// Default url goes here, pass in a nil to use it
if (url == nil) {
url = @"YourDefaultURLGoesHere";
}
NSMutableDictionary *dict = [[NSMutableDictionary alloc] initWithDictionary:params];
[dict setValue:APIKey forKey:@"APIKey"];
NSDictionary *newParams = [[NSDictionary alloc] initWithDictionary:dict];
NSURL *requestURL;
AFHTTPClient *httpClient = [[AFHTTPClient alloc] initWithBaseURL:requestURL];
NSMutableURLRequest *theRequest = [httpClient requestWithMethod:@"POST" path:url parameters:newParams];
__block NSString *responseString = @"";
AFHTTPRequestOperation *_operation = [[AFHTTPRequestOperation alloc] initWithRequest:theRequest];
__weak AFHTTPRequestOperation *operation = _operation;
[operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
responseString = [operation responseString];
id retObj = [responseString JSONValue];
// Check for invalid response (No Access)
if ([retObj isKindOfClass:[NSDictionary class]]) {
if ([[(NSDictionary *)retObj valueForKey:@"Message"] isEqualToString:@"No Access"]) {
block(nil);
[self handleNoAccessWithReason:[(NSDictionary *)retObj valueForKey:@"Reason"]];
}
} else if ([retObj isKindOfClass:[NSArray class]]) {
if ([(NSArray *)retObj count] > 0) {
NSDictionary *dict = [(NSArray *)retObj objectAtIndex:0];
if ([[dict valueForKey:@"Message"] isEqualToString:@"No Access"]) {
block(nil);
[self handleNoAccessWithReason:[(NSDictionary *)retObj valueForKey:@"Reason"]];
}
}
}
block(retObj);
}
failure:^(AFHTTPRequestOperation *operation, NSError *error) {
NSLog(@"Failed with error = %@", [NSString stringWithFormat:@"[Error]:%@",error]);
block(nil);
if (alertUserOnFailure) {
// Let the user know something went wrong
[self handleNetworkErrorWithError:operation.error];
}
}];
[operation start];
if (syncRequest) {
// Process the request syncronously
[operation waitUntilFinished];
}
}
+(void)handleNetworkErrorWithError:(NSError *)error {
NSString *errorString = [NSString stringWithFormat:@"[Error]:%@",error];
// Standard UIAlert Syntax
UIAlertView *myAlert = [[UIAlertView alloc]
initWithTitle:@"Connection Error"
message:errorString
delegate:nil
cancelButtonTitle:@"OK"
otherButtonTitles:nil, nil];
[myAlert show];
}
+(void)handleNoAccessWithReason:(NSString *)reason {
// Standard UIAlert Syntax
UIAlertView *myAlert = [[UIAlertView alloc]
initWithTitle:@"No Access"
message:reason
delegate:nil
cancelButtonTitle:@"OK"
otherButtonTitles:nil, nil];
[myAlert show];
}
@end