json解析

 RootViewController .h

#import <UIKit/UIKit.h>

@interface RootViewController : UIViewController {
    NSMutableData *responseData;
    /* 用来存放从服务器传过来的一切数据 */
    NSURLConnection *myConnection;
    /* 存放和服务器连接的对象 */
}

@end
 

 

 

RootViewController.m

#import "RootViewController.h"
#import "JSON.h"

@interface NSString (Chinese)
- (NSString *) urlEncoding;
@end
@implementation NSString (Chinese)
- (NSString *) urlEncoding
{
    NSString *retStr;
    retStr = (NSString *)CFURLCreateStringByAddingPercentEscapes(
                NULL,
                (CFStringRef)self,
                NULL,
                (CFStringRef)@";/?:@&=$+{}<>,",
                kCFStringEncodingUTF8);
    return [retStr autorelease];
}
@end

@implementation RootViewController

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

- (void)dealloc
{
    [super dealloc];
}

- (void)didReceiveMemoryWarning
{
    // Releases the view if it doesn't have a superview.
    [super didReceiveMemoryWarning];
   
    // Release any cached data, images, etc that aren't in use.
}

#pragma mark - View lifecycle

/* 把一个字符串转化成在网络上传输的标准字符串 */
- (NSString *) urlEncoding:(NSString *)str
{
    NSString *retStr;
    retStr = (NSString *)CFURLCreateStringByAddingPercentEscapes(
                    NULL,
                    (CFStringRef)str,
                    NULL,
                    (CFStringRef)@";/?:@&=$+{}<>,",
                    kCFStringEncodingUTF8);
    return [retStr autorelease];
}
/* 1. 同步网络下载 */

- (void) downloadSync
{
    NSString *str = @"http://api.douban.com/book/subjects?q=maozedong&start-index=1&max-results=10&apikey=04f1ae6738f2fc450ed50b35aad8f4cf&alt=json";
    NSURL *url = [NSURL URLWithString:str];
    /* 1. 把字符串转化为NSURL对象 */
    NSError *error = nil;
    NSString *jsonStr =
        [NSString stringWithContentsOfURL:url
                encoding:NSUTF8StringEncoding
                error:&error];
    /* 2. 同步下载url里面的内容存放在jsonStr中 */
    NSLog(@"json:%@", jsonStr);
}

- (void) downloadAsync
{
    NSString *keyWord = @"毛泽东";
    NSString *newKeyWord = [keyWord urlEncoding];
    NSString *newKeyWord2 = [self urlEncoding:keyWord];
    NSString *str = @"http://api.douban.com/book/subjects?q=maozedong&start-index=1&max-results=10&apikey=04f1ae6738f2fc450ed50b35aad8f4cf&alt=json";
    NSURL *url = [NSURL URLWithString:str];
   
    /* 0. 创建responseData数据区 */
    responseData = [[NSMutableData alloc] initWithLength:0];
    /* 1. 构造网络请求 30s超时时间 */
    NSURLRequest *myRequest =
        [NSURLRequest requestWithURL:url
            cachePolicy:NSURLRequestReturnCacheDataElseLoad
            timeoutInterval:30];
    /* 2. 建立网络连接 */
    myConnection = [[NSURLConnection alloc] initWithRequest:myRequest delegate:self];
    /* 以请求myRequest来建立一个网络连接，并且使用代理self来
     接收该连接传过来的数据 */
    /* 3. 让网络指示器显示进度条 */
    [UIApplication sharedApplication].networkActivityIndicatorVisible = YES;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    //[self downloadSync];
    [self downloadAsync];
    // Do any additional setup after loading the view from its nib.
}

- (void)viewDidUnload
{
    [super viewDidUnload];
    // Release any retained subviews of the main view.
    // e.g. self.myOutlet = nil;
}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    // Return YES for supported orientations
    return (interfaceOrientation == UIInterfaceOrientationPortrait);
}
#pragma mark -
#pragma mark Network connection
/* 1. 网络开始接收数据 */
/* 网络响应头接收完成，真正数据开始马上要来到了 */
- (void) connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
    NSLog(@"finish receive response");
    NSLog(@"response is %@", response);
    NSLog(@"begin to receive real data");
    [responseData setLength:0];
}
/* 2. 网络正在接收数据 */
/* data参数就是系统每次接收一大段数据就会调用该方法 */
- (void) connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{ 
    static int index;
    NSString *str = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
    /* 把data转化成字符串 */
   
    NSLog(@"receive index %d datastring is %@",
          index++, str);
    [str release];
    [responseData appendData:data];
    /* 把网络传给我们的数据data附加到responseData之后即可 */
}
/* 2. 网络数据接收完成 */
- (void) connectionDidFinishLoading:(NSURLConnection *)connection
{
    NSLog(@"receive finish");
    NSString *str = [[NSString alloc] initWithData:responseData encoding:NSUTF8StringEncoding];
    NSLog(@"str is %@", str);
    [UIApplication sharedApplication].networkActivityIndicatorVisible = NO;
    [myConnection release];
   
    /* 使用json解析 */
    NSDictionary *jsonParser = [str JSONValue];
    /* 通过str JSONValue就转化成 json的格式 */
    /*
     "opensearch:totalResults": {
     "$t": "3"
     },
     "opensearch:startIndex": {
     "$t": "1"
     },
     "opensearch:itemsPerPage": {
     "$t": "10"
     },
     */
    NSDictionary *t1 = [jsonParser objectForKey:@"opensearch:totalResults"];
    NSString *t2 = [t1 objectForKey:@"$t"];
    NSLog(@"$t is %@", t2);
    int startIndex = [[[jsonParser objectForKey:@"opensearch:startIndex"] objectForKey:@"$t"] intValue];
    int itemsPerPage = [[[jsonParser objectForKey:@"opensearch:itemsPerPage"] objectForKey:@"$t"] intValue];
    NSLog(@"startIndex %d itemsPerPage %d",
          startIndex, itemsPerPage);
   
    NSArray *books = [jsonParser objectForKey:@"entry"];
    for (NSDictionary *perBook in books) {
        NSString *name = [[perBook objectForKey:@"title"] objectForKey:@"$t"];
        NSString *author = [[[[perBook objectForKey:@"author"] objectAtIndex:0] objectForKey:@"name"] objectForKey:@"$t"];
        NSLog(@"book name %@ author %@", name, author);
    }
   
    [str release];
}

 @end