一、学习苹果提供的原生网络请求方法
在iOS项目开发中，网络请求是必不可少的部分，大多数iOS开发者会使用第三方的网络请求框架AFNetworking。AFNetworking基本每个iOS开发者都知道，但是却很少有人去阅读过它的源码。都会用，但却不知道它的原理，可谓是最熟悉的陌生人。要想弄懂AFNetworking的原理，首先要掌握苹果提供的原生网络请求方法，AFNetworking也是在这个基础之上进行二次封装的。本篇文章主要是介绍原生的网络请求方法，内容很简单。
NSURLSessionDataTask 是 NSURLSessionTask 的子类，是一个具体的网络请求类，是网络请求中最常用的请求之一。NSURLSessionDataTask 用来请求数据，可以用来下载数据资源，例如 JSON 数据，图片数据等。
1、NSURLSession 的实例方法一
- (NSURLSessionDataTask *)dataTaskWithURL:(NSURL *)url completionHandler:(void (^)(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error))completionHandler;
该方法中会自动将 url 转换为一个请求对象（NSURLRequest），并且该请求对象是 GET 请求方式。回调方法是在子线程中运行的，所以如果在回调方法中刷新 UI 必须回到主线程中。使用该方法的缺点是不能监听获取数据的进度，因为只有当全部请求完数据后，才会调用这个方法，也就是说，data 中的数据是请求的全部数据。
代码示例
@property (nonatomic, strong) NSURLSessionDataTask * dataTask;
self.urlString = @"https://icweiliimg9.pstatp.com/weili/l/462548014891532564.jpg";
- (void)GETButtonClick
{
self.dataTask = [[NSURLSession sharedSession] dataTaskWithURL:[NSURL URLWithString:self.urlString] completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
dispatch_async(dispatch_get_main_queue(), ^{
self.imgView.image = [UIImage imageWithData:data];
});
}];
[self.dataTask resume];
}
2、NSURLSession 的实例方法二
- (NSURLSessionDataTask *)dataTaskWithRequest:(NSURLRequest *)request completionHandler:(void (^)(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error))completionHandler;
方法一只能是GET请求方式，方法二可以手动设置请求方式GET或POST。
代码示例
- (void)PostButtonClick
{
NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:[NSURL URLWithString:self.urlString]];
request.HTTPMethod = @"POST";
self.dataTask = [[NSURLSession sharedSession] dataTaskWithRequest:request completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
dispatch_async(dispatch_get_main_queue(), ^{
self.imgView.image = [UIImage imageWithData:data];
});
}];
[self.dataTask resume];
}
3、NSURLSession 的代理方法
方法一和方法二唯一的缺点就是不能监控请求进度，因为只有当请求完全部的数据后才会调用回调方法，如果想要监控请求进度，必须使用代理的方法。
+ (NSURLSession *)sessionWithConfiguration:(NSURLSessionConfiguration *)configuration delegate:(nullable id <NSURLSessionDelegate>)delegate delegateQueue:(nullable NSOperationQueue *)queue;
代码示例
- (void)request
{
self.urlString = @"https://icweiliimg9.pstatp.com/weili/l/462548014891532564.jpg";
self.data = [[NSMutableData alloc] init];
self.session = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration] delegate:self delegateQueue:nil];
self.dataTask = [self.session dataTaskWithURL:[NSURL URLWithString:self.urlString]];
[self.dataTask resume];
}
#pragma mark 接受到数据时调用，可能会调用多次
- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveData:(NSData *)data
{
[self.data appendData:data];
dispatch_async(dispatch_get_main_queue(), ^{
NSLog(@"progress:%f",(float)self.dataTask.countOfBytesReceived);
});
}
#pragma mark 请求结束或失败时调用
- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didCompleteWithError:(NSError *)error
{
dispatch_async(dispatch_get_main_queue(), ^{
self.imgView.image = [UIImage imageWithData:self.data];
});
}
二、基于原生网络请求方法进行封装
掌握了原生的网络请求方法，我们便可以自己封装一个简单的网络请求类，在简单的项目中可以替代AFNetworking，或者可以在自己的SDK中进行使用。下面就直接上代码了，只是对文章前面的内容进行了封装。
1、HSNetworkTool.h 头文件
@interface HSNetworkTool : NSObject
+ (instancetype)shareInstance;
//请求URL
@property (nonatomic, copy) NSString *requestURL;
typedef void(^HSResponseSuccessBlock)(NSDictionary *responseObject);
typedef void(^HSResponseFailBlock)(NSError *error);
/**
* @brief GET请求方法
* @author yuancan
* @param relativePath 接口名称
* @param params 请求参数
* @param successBlock 请求成功回调
* @param failBlock 请求失败回调
*/
- (void)requestGET:(NSString *)relativePath params:(NSDictionary *)params successBlock:(HSResponseSuccessBlock)successBlock failBlock:(HSResponseFailBlock)failBlock;
/**
* @brief POST请求方法
* @author yuancan
* @param relativePath 接口名称
* @param params 请求参数
* @param successBlock 请求成功回调
* @param failBlock 请求失败回调
*/
- (void)requestPOST:(NSString *)relativePath params:(NSDictionary *)params successBlock:(HSResponseSuccessBlock)successBlock failBlock:(HSResponseFailBlock)failBlock;
/**
* @brief JSON格式网络接口请求方法
* @author yuancan
*
* @param relativePath 接口名称
* @param params 请求参数
* @param successBlock 请求成功回调
* @param failBlock 请求失败回调
*/
- (void)requestJsonPost:(NSString *)relativePath params:(NSDictionary *)params successBlock:(HSResponseSuccessBlock)successBlock failBlock:(HSResponseFailBlock)failBlock;
@end
2、HSNetworkTool.m 源文件
#import "HSNetworkTool.h"
@implementation HSNetworkTool
+ (instancetype)shareInstance
{
static HSNetworkTool *_sharedInstance = nil;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
_sharedInstance = [[HSNetworkTool alloc] init];
[_sharedInstance configure];
});
return _sharedInstance;
}
- (void)configure
{
self.requestURL = @"https://wx.ahdms.top";
}
- (void)requestHTTPMethod:(NSString *)httpMenthod relativePath:(NSString *)relativePath params:(NSDictionary *)params successBlock:(HSResponseSuccessBlock)successBlock failBlock:(HSResponseFailBlock)failBlock
{
NSMutableString *paramsString = [[NSMutableString alloc] initWithCapacity:0];
for (int i=0;i<[params allKeys].count;i++) {
NSString *key = [[params allKeys] objectAtIndex:i];
[paramsString appendString:[NSString stringWithFormat:@"%@=%@",key,[params objectForKey:key]]];
if (i < [params allKeys].count-1) {
[paramsString appendString:@"&"];
}
}
NSString *urlString = [NSString stringWithFormat:@"%@%@", self.requestURL, relativePath];
NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:[NSURL URLWithString:urlString]];
request.HTTPMethod = httpMenthod;
request.HTTPBody = [paramsString dataUsingEncoding:NSUTF8StringEncoding];
NSURLSessionDataTask *dataTask = [[NSURLSession sharedSession] dataTaskWithRequest:request completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
if (!error) {
if (successBlock) {
NSDictionary *responseObject = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:nil];
successBlock(responseObject);
}
} else {
if (failBlock) {
failBlock(error);
}
}
}];
[dataTask resume];
}
- (void)requestGET:(NSString *)relativePath params:(NSDictionary *)params successBlock:(HSResponseSuccessBlock)successBlock failBlock:(HSResponseFailBlock)failBlock
{
[self requestHTTPMethod:@"GET" relativePath:relativePath params:params successBlock:^(NSDictionary * _Nonnull responseObject) {
if (successBlock) {
return successBlock(responseObject);
}
} failBlock:^(NSError * _Nonnull error) {
if (failBlock) {
return failBlock(error);
}
}];
}
- (void)requestPOST:(NSString *)relativePath params:(NSDictionary *)params successBlock:(HSResponseSuccessBlock)successBlock failBlock:(HSResponseFailBlock)failBlock
{
[self requestHTTPMethod:@"POST" relativePath:relativePath params:params successBlock:^(NSDictionary * _Nonnull responseObject) {
if (successBlock) {
return successBlock(responseObject);
}
} failBlock:^(NSError * _Nonnull error) {
if (failBlock) {
return failBlock(error);
}
}];
}
- (void)requestJsonPost:(NSString *)relativePath params:(NSDictionary *)params successBlock:(HSResponseSuccessBlock)successBlock failBlock:(HSResponseFailBlock)failBlock
{
NSString *urlString = [NSString stringWithFormat:@"%@%@", self.requestURL, relativePath];
NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:[NSURL URLWithString:urlString]];
request.HTTPMethod = @"POST";
request.HTTPBody = [NSJSONSerialization dataWithJSONObject:params options:NSJSONWritingPrettyPrinted error:nil];
[request addValue:@"application/json; charset=utf-8" forHTTPHeaderField:@"Content-Type"];
NSURLSessionDataTask *dataTask = [[NSURLSession sharedSession] dataTaskWithRequest:request completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
if (!error) {
if (successBlock) {
NSDictionary *responseObject = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:nil];
successBlock(responseObject);
}
} else {
if (failBlock) {
failBlock(error);
}
}
}];
[dataTask resume];
}
@end
3、使用示例
GET请求
[[HSNetworkTool shareInstance] requestGET:@"/login"
params:nil
successBlock:^(NSDictionary * _Nonnull responseObject) {
}
failBlock:^(NSError * _Nonnull error) {
}];
POST请求
[[HSNetworkTool shareInstance] requestPOST:@"/login"
params:nil
successBlock:^(NSDictionary * _Nonnull responseObject) {
}
failBlock:^(NSError * _Nonnull error) {
}];
JSON格式的POST请求
[[HSNetworkTool shareInstance] requestJsonPost:@"/login"
params:nil
successBlock:^(NSDictionary * _Nonnull responseObject) {
}
failBlock:^(NSError * _Nonnull error) {
}];