我有另一个与 xCode 相关的初学者问题。我对 iOS 开发完全陌生，所以我感谢你们回复我。
我编写了以下类来访问 Restful API。如果我直接在调用方法中编写“makePostRequest”方法中的代码，它就可以正常工作。但是，我想让它异步，我不知道如何使这项工作异步。有人可以帮我把它写成异步调用吗？
#import <Foundation/Foundation.h>
#import "ServerRequest.h"
#import "NetworkHelper.h"
@implementation ServerRequest
@synthesize authorizationRequest=_authorizationRequest;
@synthesize responseContent=_responseContent;
@synthesize errorContent=_errorContent;
@synthesize url=_url;
@synthesize urlPart=_urlPart;
@synthesize token=_token;
- (void)makePostRequest : (NSString *) params {
NSString *urlString = [NSString stringWithFormat:@"%@%@", [self getUrl], [self getUrlPart]];
NSURL *url = [NSURL URLWithString:urlString];
NSURLSessionConfiguration *config = [NSURLSessionConfiguration defaultSessionConfiguration];
NSURLSession *session = [NSURLSession sessionWithConfiguration:config delegate:nil delegateQueue:[NSOperationQueue mainQueue]];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
[request setHTTPMethod:@"POST"];
[request setValue:@"application/json" forHTTPHeaderField:@"Accept"];
if([self isAuthorizationRequest]) {
[request setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"Content-Type"];
[request setValue:@"Basic" forHTTPHeaderField:@"Authorization"];
}
else {
NSString *authorizationValue = [NSString stringWithFormat:@"Bearer %@", [self getToken]];
[request setValue:authorizationValue forHTTPHeaderField:@"Authorization"];
}
if(params.length > 0)
[request setHTTPBody:[params dataUsingEncoding:NSUTF8StringEncoding]];
@try {
NSURLSessionDataTask *dataTask = [session dataTaskWithRequest:request
completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
if(error) {
NSLog(@"Error: %@", error);
}
if([response isKindOfClass:[NSHTTPURLResponse class]]) {
NSInteger statusCode = [(NSHTTPURLResponse *)response statusCode];
if(statusCode == [NetworkHelper HTTP_STATUS_CODE]) {
self.responseContent = [NSJSONSerialization JSONObjectWithData:data
options:NSJSONReadingMutableContainers|NSJSONReadingMutableLeaves
error:nil];
}
else {
self.errorContent = [NSJSONSerialization JSONObjectWithData:data
options:NSJSONReadingMutableContainers|NSJSONReadingMutableLeaves
error:nil];
}
}
}];
[dataTask resume];
}
@catch (NSException *exception) {
NSLog(@"Exception while making request: %@", exception);
} @finally {
NSLog(@"finally block here");
}
}
- (void)setAuthorization : (bool)value {
self.authorizationRequest = &value;
}
- (bool)isAuthorizationRequest {
return self.authorizationRequest;
}
- (NSDictionary *)getResponseContent {
return self.responseContent;
}
- (NSDictionary *)getErrorContent {
return self.errorContent;
}
- (void)setToken:(NSString *)token {
self.token = token;
}
- (NSString *)getToken {
return self.token;
}
- (void)setUrl:(NSString *)value {
//self.url = value;
_url = value;
}
- (NSString *)getUrl {
return self.url;
}
- (void)setUrlPart:(NSString *)value {
self.urlPart = value;
}
- (NSString *)getUrlPart {
if(self.urlPart.length == 0)
return @"";
return self.urlPart;
}
@end
我给你一个例子，你可以如何让你的方法在可用时为你提供数据。它是block基于。所以你不必在这里考虑异步任务。
首先在您的 中定义您的完成块ServerRequest.h：
typedef void(^myCompletion)(NSDictionary*, NSError*);
并将您的方法的签名更改为：
- (void) makePostRequest:(NSString *)params completion: (myCompletion)completionBlock;
现在将您的方法的实现更改为这样的（我只是发布您的@try块，所以只需更改您的 try 块。其他保持不变）
@try {
NSURLSessionDataTask *dataTask = [session dataTaskWithRequest:request
completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
if(error) {
NSLog(@"Error: %@", error);
if (completionBlock) {
completionBlock(nil, error);
}
}
if([response isKindOfClass:[NSHTTPURLResponse class]]) {
NSInteger statusCode = [(NSHTTPURLResponse *)response statusCode];
if(statusCode == [NetworkHelper HTTP_STATUS_CODE]) {
NSError *error;
self.responseContent = [NSJSONSerialization JSONObjectWithData:data
options:NSJSONReadingMutableContainers|NSJSONReadingMutableLeaves
error:&error];
if (completionBlock) {
if (error == nil) {
completionBlock(self.responseContent, nil);
} else {
completionBlock(nil, error);
}
}
} else {
NSError *error;
self.errorContent = [NSJSONSerialization JSONObjectWithData:data
options:NSJSONReadingMutableContainers|NSJSONReadingMutableLeaves
error:&error];
if (completionBlock) {
if (error == nil) {
completionBlock(self.errorContent, nil);
} else {
completionBlock(nil, error);
}
}
}
}
}];
[dataTask resume];
}
最后，当您从其他地方调用此方法时，请将其用作：
[serverRequestObject makePostRequest:@"your string" completion:^(NSDictionary *dictionary, NSError *error) {
// when your data is available after NSURLSessionDataTask's job, you will get your data here
if (error != nil) {
// Handle your error
} else {
// Use your dictionary here
}
}];
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我来说两句