網路請求AFNetworking使用量不用過多的說了，但是在開發過程中，需要用到自己去封裝一個網路請求，此處主要是說一下NSUrlSession的用法；

首先建立一個繼承與NSObject的.h和.m的類，.h中的程式碼如下：

#import <Foundation/Foundation.h>

typedef void (^CompletioBlock)(NSDictionary *dic, NSURLResponse *response, NSError *error);
typedef void (^SuccessBlock)(NSDictionary *data);
typedef void
 
 (^FailureBlock)(NSError *error);
@interface SYNetworkHelper : NSObject

/**
 *  get請求
 */
+ (void)getWithUrlString:(NSString *)url parameters:(id)parameters success:(SuccessBlock)successBlock failure:(FailureBlock)failureBlock;

/**
 * post請求
 */
+ (void)postWithUrlString:(NSString *)url parameters:(id)parameters success:(SuccessBlock)successBlock failure:(FailureBlock)failureBlock;

@end
 

.m中的實現如下：

#import "SYNetworkHelper.h"

@implementation SYNetworkHelper

+ (void)getWithUrlString:(NSString *)url parameters:(id)parameters success:(SuccessBlock)successBlock failure:(FailureBlock)failureBlock
{
    NSMutableString *mutableUrl = [[NSMutableString alloc] initWithString:url];
    if
 
 ([parameters allKeys]) {
        [mutableUrl appendString:@"?"];
        for (id key in parameters) {
            NSString *value = [[parameters objectForKey:key] stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLQueryAllowedCharacterSet]];
            [mutableUrl appendString:[NSString stringWithFormat:@"%@=%@&", key, value]];
        }
    }
    NSString *urlEnCode = [[mutableUrl substringToIndex:mutableUrl.length - 1] stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLQueryAllowedCharacterSet]];
    NSURLRequest *urlRequest = [NSURLRequest requestWithURL:[NSURL URLWithString:urlEnCode]];
    NSURLSession *urlSession = [NSURLSession sharedSession];
    NSURLSessionDataTask *dataTask = [urlSession dataTaskWithRequest:urlRequest completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
        if (error) {
            failureBlock(error);
        } else {
            NSDictionary *dic = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers error:nil];
            successBlock(dic);
        }
    }];
    [dataTask resume];
}

+ (void)postWithUrlString:(NSString *)url parameters:(id)parameters success:(SuccessBlock)successBlock failure:(FailureBlock)failureBlock
{
    NSURL *nsurl = [NSURL URLWithString:url];
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:nsurl];
    //如果想要設定網路超時的時間的話，可以使用下面的方法：
    //NSMutableURLRequest *mutableRequest=[NSMutableURLRequest requestWithURL:[NSURL URLWithString:url] cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:10];
    //設定請求型別
    request.HTTPMethod = @"POST";
    NSString *postStr = [SYNetworkHelper parseParams:parameters];
    //把引數放到請求體內
    request.HTTPBody = [postStr dataUsingEncoding:NSUTF8StringEncoding];
    NSURLSession *session = [NSURLSession sharedSession];
    NSURLSessionDataTask *dataTask = [session dataTaskWithRequest:request completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
        if (error) { //請求失敗
            failureBlock(error);
        } else {  //請求成功
            NSDictionary *dic = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers error:nil];
            successBlock(dic);
        }
    }];
    [dataTask resume];  //開始請求
}

//把NSDictionary解析成post格式的NSString字串
+ (NSString *)parseParams:(NSDictionary *)params
{
    NSString *keyValueFormat;
    NSMutableString *result = [NSMutableString new];
    NSMutableArray *array = [NSMutableArray new];
    //例項化一個key列舉器用來存放dictionary的key
    NSEnumerator *keyEnum = [params keyEnumerator];
    id key;
    while (key = [keyEnum nextObject]) {
        keyValueFormat = [NSString stringWithFormat:@"%@=%@&", key, [params valueForKey:key]];
        [result appendString:keyValueFormat];
        [array addObject:keyValueFormat];
    }
    return result;
}

@end