NSURLConnection发送Get网络请求

//
//  ViewController.m
//  NSURLConnection使用
//
//  Created by 李圣培 on 2019/3/15.
//  Copyright © 2019年 李圣培. All rights reserved.
//

#import "ViewController.h"

@interface ViewController ()<NSURLConnectionDataDelegate>

@property (nonatomic, strong) NSMutableData   *totalData;

@end

@implementation ViewController

-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{
    
//    [self getYahooData];//同步请求，会阻塞主线程
//    [self getYahooData_GCD];//使用GCD把同步请求放在子线程中，也不会阻塞主线程
//    [self getYahooData_Async];//直接使用异步请求，不会阻塞主线程
      [self getYahooData_delegate];
}

-(NSMutableData *)totalData
{
    if (_totalData == nil) {
        _totalData = [[NSMutableData alloc]init];
    }
    return _totalData;
}

-(void)getYahooData_Async
{
    NSLog(@"异步请求测试开始...");
    NSURL *url = [NSURL URLWithString:@"http://www.yahoo.com"];
    NSURLRequest *request = [NSURLRequest requestWithURL:url];
    
    NSLog(@"马上进行异步连接请求url的数据");
    [NSURLConnection sendAsynchronousRequest:request queue:[NSOperationQueue currentQueue] completionHandler:^(NSURLResponse * _Nullable response, NSData * _Nullable data, NSError * _Nullable connectionError) {//[NSOperationQueue currentQueue]决定block在哪个队列执行
        
        if (data.length > 0 && connectionError == nil) {
            NSLog(@"%lu字节的数据被返回",(unsigned long)data.length);
        }else if (connectionError == nil && data.length == 0)
        {
            NSLog(@"没有数据返回。。");
        }else if (connectionError != nil)
        {
            NSLog(@"返回错误");
        }
    }];
    NSLog(@"异步请求测试完成。。");
}

-(void)getYahooData_GCD
{
    NSLog(@"异步请求测试开始...");
    NSURL *url = [NSURL URLWithString:@"http://www.yahoo.com"];
    NSURLRequest *request = [NSURLRequest requestWithURL:url];
    
    NSLog(@"马上进行异步连接请求url的数据");
    dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
    dispatch_async(queue, ^{
        
        NSURLResponse *response = nil;
        NSError *error = nil;
       
        NSData *data = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error];
        
        if (data.length > 0 && error == nil) {
            NSLog(@"%lu字节的数据被返回",(unsigned long)data.length);
        }else if (error == nil && data.length == 0)
        {
            NSLog(@"没有数据返回。。");
        }else if (error != nil)
        {
            NSLog(@"返回错误");
        }
    });
    
    NSLog(@"GCD测试完成。。");
}

-(void)getYahooData
{//同步请求，会阻塞主线程
    NSLog(@"同步请求测试开始...");
    NSURL *url = [NSURL URLWithString:@"http://www.yahoo.com"];
    NSURLRequest *request = [NSURLRequest requestWithURL:url];
    
    NSURLResponse *response = nil;
    NSError *error = nil;
    
    NSLog(@"马上进行同步连接请求url的数据");
    NSData *data = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error];
    
    if (data.length > 0 && error == nil) {
        NSLog(@"%lu字节的数据被返回",(unsigned long)data.length);
    }else if (error == nil && data.length == 0)
    {
        NSLog(@"没有数据返回。。");
    }else if (error != nil)
    {
        NSLog(@"返回错误");
    }
    NSLog(@"%@",[[NSString alloc]initWithData:data encoding:NSUTF8StringEncoding]);
    
}

-(void)getYahooData_delegate
{
    NSURL *url = [NSURL URLWithString:@"http://www.yahoo.com"];
    NSURLRequest *request = [NSURLRequest requestWithURL:url];
    
    NSURLConnection *connection = [[NSURLConnection alloc]initWithRequest:request delegate:self];
    
    //如果使用这个方法startImmediately设置为NO，则需要手动调用start开启网络请求。
//    NSURLConnection *connection = [[NSURLConnection alloc]initWithRequest:request delegate:self startImmediately:NO];
//    [connection start];
    
//    [connection cancel];请求取消
}

#pragma mark NSURLConnectionDataDelegate

- (NSURLRequest *)connection:(NSURLConnection *)connection willSendRequest:(NSURLRequest *)request redirectResponse:(nullable NSURLResponse *)response
{
    return request;
}
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{//接收到服务器的响应
    
}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{//接收到服务返回的数据， 可能会调用多次,在这里拼接数据
    [self.totalData appendData:data];
    NSLog(@"-----totalData Length: %lu",_totalData.length);
}

- (void)connection:(NSURLConnection *)connection   didSendBodyData:(NSInteger)bytesWritten
 totalBytesWritten:(NSInteger)totalBytesWritten totalBytesExpectedToWrite:(NSInteger)totalBytesExpectedToWrite
{
    
}

- (nullable NSCachedURLResponse *)connection:(NSURLConnection *)connection willCacheResponse:(NSCachedURLResponse *)cachedResponse
{
    NSLog(@"%@",cachedResponse);
    return cachedResponse;
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{//请求完成时调用
    NSLog(@"connectionDidFinishLoading");
    
    NSLog(@"totalData Length: %lu",self.totalData.length);
    NSLog(@"%@",[[NSString alloc]initWithData:self.totalData encoding:NSUTF8StringEncoding]);
}

@end