iOS Get同步與異步

//異步所需要簽訂的協議

@interfaceGetViewController ()<NSURLConnectionDelegate,NSURLConnectionDataDelegate>

//聲明一個鏈接屬性,主要用是在頁面銷燬但加載還沒完成的時候,在dealloc上終止用的

@property (nonatomic,retain)NSURLConnection *connection;

//聲明一個可變的data用於獲取到完整的data;,注意在那裏初始化

@property (nonatomic,retain)NSMutableData *receiveData;

- (void)dealloc
{
    //注意:當這個頁面被銷燬的時候如果請求還沒有完成需要終止這個鏈接
    [_connectioncancel];
    [_connectionrelease];
    [superdealloc];

}

-----------------------------------------------------------------------

#define kSearchURL @"http://api.map.baidu.com/place/v2/search?query=公廁&region=上海&output=json&ak=6E823f587c95f0148c19993539b99295"

#define kNewsListURL @"http://ipad-bjwb.bjd.com.cn/DigitalPublication/publish/Handler/APINewsList.ashx"
#define kNewsListParam @"date=20131129&startRecord=1&len=30&udid=1234567890&terminalType=Iphone&cid=213"

#define kImageURL @"http://image.zcool.com.cn/56/13/1308200901454.jpg"

-------------------------------------------------------------------------

get同步

// 如果有中文轉化一下編碼格式

NSString *newStr = [kSearchURL stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSetURLFragmentAllowedCharacterSet]];

//把字符串的網址轉化成網址對象
    NSURL *url = [NSURLURLWithString:newStr];

    //創建一個請求
    //timeoutInterval請求超時的時間秒爲單位
    NSMutableURLRequest *request = [NSMutableURLRequestrequestWithURL:urlcachePolicy:(NSURLRequestUseProtocolCachePolicy)timeoutInterval:10];

    //設置一個請求標識

[request setHTTPMethod:@"Get"];

   //利用這個請求創建一個鏈接
    NSError *error = nil;
    //創建空的,服務器響應信息
    NSURLResponse *response = nil;
    //建立同步鏈接並得到返回的數據(data)

NSData *data = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error];

   //解析數據
    NSMutableDictionary *dataDic = [NSJSONSerialization JSONObjectWithData:data options:(NSJSONReadingMutableContainers) error:nil];

    NSLog(@"%@",dataDic);

    NSLog(@"%@",response);

    NSLog(@"%@",data);

------------------------------------------------------------------------

//get異步請求

    //獲取網址對象 (有中文需要轉碼)
    NSString *urlStr = [kSearchURL stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLFragmentAllowedCharacterSet]];

    //利用網址創建網址對象
    NSURL *url = [NSURL URLWithString:urlStr];

    //利用網址對象創建一個請求
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url cachePolicy:(NSURLRequestUseProtocolCachePolicy) timeoutInterval:10];

    //標識請求類型
    //注意:加標識符

[request setHTTPMethod:@"Get"];

-------------------------------------------------------

#pragma mark -- block異步鏈接方法

[NSOperationQueue mainQueue]

代表回到主線程

[NSURLConnection sendAsynchronousRequest:request queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse * _Nullable response, NSData * _Nullable data, NSError * _Nullable connectionError) {

//當數據請求完成的時候會指定這個block

NSLog(@"%@",data);

//判斷是否在主線程

NSLog(@"%d",[NSThread isMainThread]);

}];

-------------------------------------------------------------------
#pragma mark -- 代理方法異步鏈接

    //利用請求創建一個異步鏈接
    self.connection = [NSURLConnection connectionWithRequest:requestdelegate:self];
    //開始鏈接
    [self.connectionstart];

---------------------------------------------------------------------

#pragma mark --代理方法

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
    //鏈接成功時創建data
    self.receiveData = [NSMutableData data];

    NSLog(@"已經接收到服務器的響應信息,說明鏈接成功");
    NSLog(@"%@",response);
}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
    //多次觸發這個方法才能接收到完整的data
    //所以這個時候需要拼接一下data

    //拼接data
    [self.receiveData appendData:data];

    NSLog(@"接收到數據觸發的方法");
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    NSLog(@"%@",self.receiveData);
    //解析數據
    NSMutableDictionary *dataDic = [NSJSONSerialization JSONObjectWithData:self.receiveData options:(NSJSONReadingMutableContainers)error:nil];
    NSLog(@"%@",dataDic);

    //如果在tableView上展示的話
    //注意:要刷新界面

    NSLog(@"已經完成數據加載觸發的方法");
}

//請求失敗時觸發
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
    NSLog(@"請求失敗時觸發 %@",error);

}

UI第十六天 16-NSURLRequest