Objective-c 网络编程1 Web请求和响应

//
//  ViewController.m
//  网络编程
//
//  Created by DC017 on 15/12/9.
//  Copyright © 2015年 DC017. All rights reserved.
//

#import "ViewController.h"

@interface ViewController ()<NSURLConnectionDataDelegate>
{
UITextField *textfield;
UILabel* label;
UIButton *button;
UIProgressView *progress;
NSMutableData * mudata;
long long totalLength;
}

@end

@implementation ViewController

- (void)viewDidLoad {
[super viewDidLoad];

[self buju];

}
-(void)buju{

textfield =[[UITextField alloc]initWithFrame:CGRectMake(10, 60, 300, 30)];
textfield.layer.borderWidth=2;
textfield.layer.cornerRadius=7;
textfield.text=@"http://b.zol-img.com.cn/desk/bizhi/image/7/1920x1080/1449126103556.jpg";
textfield.layer.borderColor=[UIColor blackColor].CGColor;
[self.view addSubview:textfield];

progress=[[UIProgressView alloc]initWithFrame:CGRectMake(10, 100, 300,2 )];
progress.backgroundColor=[UIColor whiteColor];
[self.view addSubview:progress];

label =[[UILabel alloc]initWithFrame:CGRectMake(10, 130, 100, 20)];
label.textColor=[UIColor blackColor];
label.text=@"请下载";

[self.view addSubview:label];

button=[[UIButton alloc]initWithFrame:
CGRectMake(40, 400, 50, 20)];

[button setTitle:@"下载" forState:UIControlStateNormal];
[button setTitleColor:[UIColor redColor] forState:UIControlStateNormal];
button.layer.borderWidth=1;
button.layer.borderColor=[UIColor redColor].CGColor;
button.layer.cornerRadius=8;
[self.view addSubview:button];

[button addTarget:self action:@selector(xiazai) forControlEvents:UIControlEventTouchUpInside];

}

-(void)xiazai{
NSLog(@"下载");
NSString * tri=textfield.text;
//新版
//tri=[tri stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLFragmentAllowedCharacterSet]];

//旧版
tri=[tri stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

NSURL *url=[NSURL URLWithString:tri];

//创建请求
NSURLRequest *request=[[NSURLRequest alloc]initWithURL:url cachePolicy:0 timeoutInterval:15.0f];

//创建连接
NSURLConnection * Connection=[[NSURLConnection alloc]initWithRequest:request delegate:self];

//启动连接
[Connection start];

}
#pragma mark -开始代理 的四种方法

#pragma mark 开始接收响应
-(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response{
NSLog(@"接收响应");
mudata=[[NSMutableData alloc]init];
//初始化进度条
progress.progress=0;
NSLog(@"%@",response);

//处理响应;
//通过响应头中

NSHTTPURLResponse * httpurl=(NSHTTPURLResponse *)response;
NSDictionary * head=[httpurl allHeaderFields];
NSLog(@"%@",head);

totalLength =[head [@"Content-Length"]longLongValue];

NSLog(@"%lld",totalLength);

}
#pragma mark 接收数据
-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data{
NSLog(@"接收数据");

[mudata appendData:data];
//更新进度条

[self gengxinjindutiao];

}
#pragma mark 数据接收完成
-(void)connectionDidFinishLoading:(NSURLConnection *)connection{
NSLog(@"数据接收完成");
//数据保存苹果官方要求只能保存到缓存里
NSString *path=[NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES)lastObject];

NSLog(@"%@",path);
path=[path stringByAppendingPathComponent:@"下载图片01.jpg"];
//保存下载内容
[mudata writeToFile:path atomically:YES];

}

#pragma mark 请求数据失败
-(void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error{
NSLog(@"请求失败 原因是：%@",error);
}

-(void)gengxinjindutiao{
if (mudata.length==totalLength) {
label.text=@"下载完成";
}
else{
label.text=@"正在下载";

}
progress.progress=(float)mudata.length/totalLength;

}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}

@end