study note: IOS之同步请求、异步请求、GET请求、POST请求

Apple is not longer supported " NSURLConnection sendSynchronousRequest "  

1、同步请求可以从因特网请求数据，一旦发送同步请求，程序将停止用户交互，直至服务器返回数据完成，才可以进行下一步操作，
2、异步请求不会阻塞主线程，而会建立一个新的线程来操作，用户发出异步请求后，依然可以对UI进行操作，程序可以继续运行
3、GET请求，将参数直接写在访问路径上。操作简单，不过容易被外界看到，安全性不高，地址最多255字节；
4、POST请求，将参数放到body里面。POST请求操作相对复杂，需要将参数和地址分开，不过安全性高，参数放在body里面，不易被捕获。

Objective C

1、 同步GET请求

//第一步，创建URL

NSURL *url = [NSURL URLWithString:@"http://api.hudong.com/iphonexml.do?type=focus-c"];

//第二步，通过URL创建网络请求

NSURLRequest *request = [[NSURLRequest alloc]initWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:10];

//NSURLRequest初始化方法第一个参数：请求访问路径，第二个参数：缓存协议，第三个参数：网络请求超时时间（秒）

其中缓存协议是个枚举类型包含：

NSURLRequestUseProtocolCachePolicy（基础策略）

NSURLRequestReloadIgnoringLocalCacheData（忽略本地缓存）

NSURLRequestReturnCacheDataElseLoad（首先使用缓存，如果没有本地缓存，才从原地址下载）

NSURLRequestReturnCacheDataDontLoad（使用本地缓存，从不下载，如果本地没有缓存，则请求失败，此策略多用于离线操作）

NSURLRequestReloadIgnoringLocalAndRemoteCacheData（无视任何缓存策略，无论是本地的还是远程的，总是从原地址重新下载）

NSURLRequestReloadRevalidatingCacheData（如果本地缓存是有效的则不下载，其他任何情况都从原地址重新下载）

//第三步，连接服务器

NSData *received = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];

NSString *str = [[NSString alloc]initWithData:received encoding:NSUTF8StringEncoding];

NSLog(@"%@",str);

//该代码片段来自于: http://www.sharejs.com/codes/objectc/5873

2、同步POST请求

//第一步，创建URL

NSURL *url = [NSURL URLWithString:@"http://api.hudong.com/iphonexml.do"];

//第二步，创建请求

NSMutableURLRequest *request = [[NSMutableURLRequest alloc]initWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:10];

[request setHTTPMethod:@"POST"];//设置请求方式为POST，默认为GET

NSString *str = @"type=focus-c";//设置参数

NSData *data = [str dataUsingEncoding:NSUTF8StringEncoding];

[request setHTTPBody:data];

//第三步，连接服务器

NSData *received = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];

NSString *str1 = [[NSString alloc]initWithData:received encoding:NSUTF8StringEncoding];

NSLog(@"%@",str1);

//该代码片段来自于: http://www.sharejs.com/codes/objectc/5873

3、异步GET请求

//第一步，创建url

NSURL *url = [NSURL URLWithString:@"http://api.hudong.com/iphonexml.do?type=focus-c"];

//第二步，创建请求

NSURLRequest *request = [[NSURLRequest alloc]initWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:10];

//第三步，连接服务器

NSURLConnection *connection = [[NSURLConnection alloc]initWithRequest:request delegate:self];

//该代码片段来自于: http://www.sharejs.com/codes/objectc/5873

4、异步POST请求

//第一步，创建url

NSURL *url = [NSURL URLWithString:@"http://api.hudong.com/iphonexml.do"];

//第二步，创建请求

NSMutableURLRequest *request = [[NSMutableURLRequest alloc]initWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:10];

[request setHTTPMethod:@"POST"];

NSString *str = @"type=focus-c";

NSData *data = [str dataUsingEncoding:NSUTF8StringEncoding];

[request setHTTPBody:data];

//第三步，连接服务器

NSURLConnection *connection = [[NSURLConnection alloc]initWithRequest:request delegate:self];

//该代码片段来自于: http://www.sharejs.com/codes/objectc/5873

5、异步请求的代理方法

view source

print?

//接收到服务器回应的时候调用此方法

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response

{

NSHTTPURLResponse *res = (NSHTTPURLResponse *)response;

NSLog(@"%@",[res allHeaderFields]);

self.receiveData = [NSMutableData data];

}

//接收到服务器传输数据的时候调用，此方法根据数据大小执行若干次

-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data

{

[self.receiveData appendData:data];

}

//数据传完之后调用此方法

-(void)connectionDidFinishLoading:(NSURLConnection *)connection

{

NSString *receiveStr = [[NSString alloc]initWithData:self.receiveData encoding:NSUTF8StringEncoding];

NSLog(@"%@",receiveStr);

}

//网络请求过程中，出现任何错误（断网，连接超时等）会进入此方法

-(void)connection:(NSURLConnection *)connection

didFailWithError:(NSError *)error

{

NSLog(@"%@",[error localizedDescription]);

}

//该代码片段来自于: http://www.sharejs.com/codes/objectc/5873

grand central dispatch

Last week,  through a mini project I got to work on GCD for the first time and all of the sudden it started making sense to me.


So the project loads a tableview of a list of Guests type.  In the cell,

1. on main thread, label loads the name of the guests from firebase , and the imageView loads a placeholder image temperily. 
2. and on the separated thread the photos of the guests(a cat picture in this sample) being loaded and replace the placeholder image once it is done downloading from Firebase storeage. 

https://github.com/lingzt/FirebaseDatabasePra

grand central dispatch

Last week,  through a mini project I got to work on GCD for the first time and all of the sudden it started making sense to me.


So the project loads a tableview of list of Guests type.  In the cell,

1. on main thread, label loads the name of the guests from firebase , and the imageView loads a placeholder image temperily. 
2. and on the separated thread the photos of the guests(a cat picture in this sample) being loaded and replace the placeholder image once it is done downloading from Firebase storeage. 

https://github.com/lingzt/FirebaseDatabasePra

Supper cool way to store Array to Firebase

https://firebase.googleblog.com/2014/04/best-practices-arrays-in-firebase.html
Great article, I was really confused at the beginning. However, the magic happens.

I store a JSON file to firebase,

{
"guest": {
"randomGidForGuestOne":{
"gid": "randomGidForGuestOne",
"guestAndPlusOneNumber": "1",
"guestAndPlusOneList":{"0": "randomGidForGuestOne","1":"randomGidForGuestTwo"},
"gImage":"gs://fir-databasepra.appspot.com/guestImage/randomGidForGuestOne.png"
},
"randomGidForGuestTwo":{
"gid": "randomGidForGuestTwo",
"guestAndPlusOneNumber": "0",
"guestAndPlusOneList":{"0": "randomGidForGuestTwo"}
}
}
}

and got back a dictionary with array in snapshot.  So it looks like this


{
"guest": {
"randomGidForGuestOne":{
"gid": "randomGidForGuestOne",
"guestAndPlusOneNumber": "1",
"guestAndPlusOneList": ["randomGidForGuestOne","randomGidForGuestTwo"],
"gImage":"gs://fir-databasepra.appspot.com/guestImage/randomGidForGuestOne.png"
},
"randomGidForGuestTwo":{
"gid": "randomGidForGuestTwo",
"guestAndPlusOneNumber": "0",
"guestAndPlusOneList":{"0": "randomGidForGuestTwo"}
}
}
}

Supper cool!!! Detail please see github.

https://github.com/lingzt/FirebaseDatabasePra/commit/e282cac346e747b22a669d26d000bb7e84caecb3 

Vocation? Work from home?

A whole week break after demo day was a little rough.  I am really having a hard time slowing things down.

Basically I am working on this Apache Spark course from UCBerkeley for the week. Progress has been made, it has just been slow...................

Somehow I feel Spark will come handy one day,  I think.  It's worth my time.

SeatHero day10

2 weeks into SeatHero.
So far, have the key function half way done. Sign up and Log in done. Way to go.

All of the sudden I feel the pressure of the deadlines.