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xml和json

xml：兩種解析方式 dom 和 sax

dom 把整個數據一次性讀入內存，功耗大，解析難度低

sax 逐步解析，內存小，相對麻煩

json

相對好點。

#import <Foundation/Foundation.h>
typedef void (^FinishConnection)(NSData *data);

@interface WXRequest : NSMutableURLRequest <NSURLConnectionDataDelegate>

@property (nonatomic, retain) NSMutableData *data;
@property (nonatomic, retain) NSURLConnection *connection;
@property (nonatomic, copy) FinishConnection block;
- (void)startAsynrc;
- (void)cancel;
@end

#import "WXRequest.h"

@implementation WXRequest

- (void)startAsynrc
{
    self.data = [NSMutableData data];
    self.connection = [NSURLConnection connectionWithRequest:self delegate:self];
}

- (void)cancel
{
    [self.connection cancel];
}

#pragma mark NSURLConnection delegate
//receive data
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
    [self.data appendData:data];
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    self.block(self.data);
}

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
    NSLog(@"請求數據失敗 %@", error);
}
@end

#import <Foundation/Foundation.h>
typedef void (^completion)(id);
@interface WXDataService : NSObject
+ (void)getWetherData:(NSDictionary *)params block:(completion)block;
@end

#import "WXDataService.h"
#import "WXRequest.h"
#define BASE_URL @"http://www.weather.com.cn/data/sk/"
@implementation WXDataService

+ (void)getWetherData:(NSDictionary *)params block:(completion)block
{
    NSString *cityCode = [params objectForKey:@"code"];
    NSString *urlstring = [BASE_URL stringByAppendingFormat:@"%@.html", cityCode];
    [self startRequest:params url:urlstring isGet NO block:block];
}

+ (void)startRequest:(NSDictionary *)params url:(NSString *)url isGet:(BOOL)get block:(completion)block
{
    WXRequest *request = [WXRequest requestWithURL:[NSURL URLWithString:url]];
    if (get){
        [request setHTTPMethod:@"GET"];
    }else{
        [request setHTTPMethod:@"POST"];
        //user=gg&pwd=tt
    }
    
    [request setTimeoutInterval:60];
    request.block = ^(NSData *data){
        NSString *datastring = [[NSString alloc]initWithData:data encoding:NSUTF8StringEncoding];
        NSLog(@"json : %@", datastring);
        
        id ret = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers error:nil];
        block(ret);
    };
    [request startAsynrc];
}
@end