Question

如何为iOS实现-[NSURLConnection sendAsynchronousRequest:queue:completionHandler:]＆lt; 5？

#if __IPHONE_OS_VERSION_MIN_REQUIRED < __IPHONE_5_0

#import <objc/runtime.h>
#import "NSURLConnection+iOS4.h"

// Dynamically add -[NSURLConnection sendAsynchronousRequest:queue:completionHandler:].
void *sendAsynchronousRequest4(id self, SEL _cmd, NSURLRequest *request, NSOperationQueue *queue, void (^handler)(NSURLResponse*, NSData*, NSError*));
void *sendAsynchronousRequest4(id self, SEL _cmd, NSURLRequest *request, NSOperationQueue *queue, void (^handler)(NSURLResponse*, NSData*, NSError*)) {

    // How should we implement this?

}

@implementation NSURLConnection (SendAsync)

+ (void)load {
    SEL sendAsyncSelector = @selector(sendAsynchronousRequest:queue:completionHandler:);
    if (![NSURLConnection instancesRespondToSelector:]) {
        class_addMethod([self class], sendAsyncSelector, (IMP)sendAsynchronousRequest4, "v@:@@@");
    }
}

@end

#endif

Answer 1

// NSURLConnection+SendAsync.h

#if __IPHONE_OS_VERSION_MIN_REQUIRED < __IPHONE_5_0

#import <Foundation/Foundation.h>

@interface NSURLConnection (SendAsync)

@end

#endif


// NSURLConnection+SendAsync.m

#if __IPHONE_OS_VERSION_MIN_REQUIRED < __IPHONE_5_0

typedef void (^URLConnectionCompletionHandler)(NSURLResponse *response, NSData *data, NSError *error);

@interface URLConnectionDelegate : NSObject <NSURLConnectionDataDelegate>

@property (nonatomic, strong) NSURLResponse *response;
@property (nonatomic, strong) NSMutableData *data;
@property (nonatomic, strong) NSOperationQueue *queue;
@property (nonatomic, copy) URLConnectionCompletionHandler handler;

@end 

@implementation URLConnectionDelegate 

@synthesize response;
@synthesize data;
@synthesize queue;
@synthesize handler;

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)theResponse {
    self.response = theResponse;
    [data setLength:0]; // reset data
}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)theData {
    [data appendData:theData]; // append incoming data
}

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {
    [UIApplication sharedApplication].networkActivityIndicatorVisible = NO;
    self.data = nil;
    if (handler) { [queue addOperationWithBlock:^{ handler(response, nil, error); }]; }
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
    [UIApplication sharedApplication].networkActivityIndicatorVisible = NO;
    // TODO: Are we passing the arguments to the block correctly? Should we copy them?
    if (handler) { [queue addOperationWithBlock:^{ handler(response, data, nil); }]; }
}

@end

#import <objc/runtime.h>
#import "NSURLConnection+SendAsync.h"

// Dynamically add @property (nonatomic,readonly) UIViewController *presentingViewController.
void sendAsynchronousRequest4(id self, SEL _cmd, NSURLRequest *request, NSOperationQueue *queue,
                              URLConnectionCompletionHandler handler);
void sendAsynchronousRequest4(id self, SEL _cmd, NSURLRequest *request, NSOperationQueue *queue,
                              URLConnectionCompletionHandler handler) {

    URLConnectionDelegate *connectionDelegate = [[URLConnectionDelegate alloc] init];
    connectionDelegate.data = [NSMutableData data];
    connectionDelegate.queue = queue;
    connectionDelegate.handler = handler;
    NSURLConnection *connection = [NSURLConnection connectionWithRequest:request
                                                                delegate:connectionDelegate];
    NSAssert(connection, nil);
}

@implementation NSURLConnection (SendAsync)

+ (void)load {
    SEL sendAsyncSelector = @selector(sendAsynchronousRequest:queue:completionHandler:);
    if (![NSURLConnection instancesRespondToSelector:sendAsyncSelector]) {
        class_addMethod(object_getClass([self class]),
                        sendAsyncSelector, (IMP)sendAsynchronousRequest4, "v@:@@@");
    }
}

@end

#endif

Answer 2

我通常创建一个NSOperation的子类，并在操作的main方法中执行同步请求。为了调用操作，我创建了一个子类的实例并将其抛给队列（而不是主线程）。然后，当操作完成时，它可以使用收到的数据调用委托，也可以通过NSNotificationCenter发布通知。

Answer 3

我会使用已经构建的框架，如ASIHTTPRequest（不再开发，但仍然非常好）或RestKit（我之前从未使用它，但听说它很不错）。这些将在不同版本的操作系统中为您提供相同的功能（异步http请求）。

ifdefs不是那种方法，因为它们是在编译时完成的，你不会为每个平台编译应用程序的单独版本。

你可能会在运行时做一些恶作剧，但它似乎比它的价值更麻烦。

iOS4的实现 - [NSURLConnection sendAsynchronousRequest：queue：completionHandler：]？

3 个答案: