基础Network Request

1：NSData + NSURL

- (void)FF_LoadImageWithURLString:(NSString *)urlStr imageBlock:(ImageBlock)imageRequestCompleteBlock {
    if (urlStr && urlStr.length > 0) {
        dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
            NSData *data = [NSData dataWithContentsOfURL:[NSURL URLWithString:urlStr]];
            dispatch_async(dispatch_get_main_queue(), ^{
                imageRequestCompleteBlock([UIImage imageWithData:data]);
            });
        });
    }
}

*  通过NSMutableRequest 来指定请求的方式(HTTPMethod)请求体(HTTPBody)等

2: NSURLConnection (已经被废弃)

可以通过Block或者delegate的形式来获取请求完成的数据

- (void)FF_loadDataUseNSURLConnection:(NSString *)url block:(ImageBlock)completeBlock {
    NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:url]];
    /// 异步请求
    [NSURLConnection sendAsynchronousRequest:request queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse * _Nullable response, NSData * _Nullable data, NSError * _Nullable connectionError) {
        /// 在主线程中
        completeBlock([UIImage imageWithData:data]);
    }];
    NSLog(@"是异步执行");
}

deleaget形式

- (void)FF_LoadDataUseNSURLConnectionDelegate:(NSString *)url block:(ImageBlock)completeBlock {
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:url]];
    request.HTTPMethod = @"post";
    request.HTTPBody = [@"" dataUsingEncoding:NSUTF8StringEncoding];
    [NSURLConnection connectionWithRequest:request delegate:self];
    self.needBlcok = completeBlock;
}

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {
    long mm = response.expectedContentLength;
    
    self.mdata = [NSMutableData data];
    
    NSLog(@"收到响应 %.2f", mm / 1024.0 / 1024);
}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
    [self.mdata appendData:data];
    NSLog(@"收到数据");
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
    self.needBlcok([UIImage imageWithData:self.mdata]);
    NSLog(@"借宿请求");
}

3： NSURLSession

- (void)FF_LoadDataUseNSURLSession:(NSString *)url block:(ImageBlock)completeblock {
    [NSURLSession sharedSession];
    //NSURLSessionDataTask NSURLSessionUploadTask NSURLSessionDownloadTask
    
    NSURLSessionDataTask *task = [[NSURLSession sharedSession] dataTaskWithURL:[NSURL URLWithString:url] completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
        dispatch_async(dispatch_get_main_queue(), ^{
            // 将JSON数据转化成Object
            NSDictionary *dic = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers error:nil];
            NSLog(@"%@", dic);
//            completeblock([UIImage imageWithData:data]);
        });
    }];
    [task resume];
}

delegate形式

- (void)FF_LoadDataUseNSURLSessionDelgate:(NSString *)url block:(ImageBlock)completeBlock {
    NSURLSession *session = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration] delegate:self delegateQueue:[NSOperationQueue mainQueue]];
    NSURLSessionDataTask *task = [session dataTaskWithURL:[NSURL URLWithString:url]];
    self.needBlcok = completeBlock;
    [task resume];
}

- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask
didReceiveResponse:(NSURLResponse *)response
 completionHandler:(void (^)(NSURLSessionResponseDisposition disposition))completionHandler {
    self.mdata = [NSMutableData data];
    /// 允许响应
    completionHandler(NSURLSessionResponseAllow);
    NSLog(@"开始响应");
}

- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask
    didReceiveData:(NSData *)data {
    [self.mdata appendData:data];
    NSLog(@"收到数据");
}

- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task
didCompleteWithError:(nullable NSError *)error {
    if (error == nil) {
        self.needBlcok([UIImage imageWithData:self.mdata]);
    }
    NSLog(@"完成请求");
}

- (void)URLSession:(NSURLSession *)session didBecomeInvalidWithError:(nullable NSError *)error {
    NSLog(@"出现错误 %@", error.localizedDescription);
}

XML 解析 SAX， DOM

SAX解析（Simple API XML）逐行读入  可以立即停止解析，速度快，适用于读取 ，但是不能对XML进行修改

<?xml version="1.0" encoding="utf-8" ?>
<!--不引用任何的css文件，此时就能提取出所有的信息，标签除外，此种情况会将所有除标签之外的内容提出出来，排列在一行，当然我们可指定css文件改变这种布局-->
<?xml-stylesheet type="text/css" href="a.css" ?>
<contactlist>
    <contect id="001">
        <name>张三</name>
        <telephone>120</telephone>
    </contect>

    <contect id="002">
        <name>李四</name>
        <telephone>110</telephone>
    </contect>
</contactlist>


    /// 生成解析器 系统自带
    NSString *path = [[NSBundle mainBundle] pathForResource:@"aa" ofType:@"xml"];
    NSData *data = [NSData dataWithContentsOfFile:path];
    NSXMLParser *parser = [[NSXMLParser alloc] initWithData:data];
    parser.delegate = self;
    if (parser) {
        NSLog(@"....");
    }else {
        NSLog(@"不存在。。。");
    }
    /// 开始解析
    BOOL bl = [parser parse];
    if (bl) {
        NSLog(@"---");
    }else {
        NSLog(@"+++");
    }

/// 代理
/// 系统自带的SAX（simple api xml）解析
- (void)parserDidStartDocument:(NSXMLParser *)parser {
    NSLog(@"开始解析");
    self.marr = [@[] mutableCopy];
}

/// 开始的元素
- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(nullable NSString *)namespaceURI qualifiedName:(nullable NSString *)qName attributes:(NSDictionary<NSString *, NSString *> *)attributeDict {
    NSLog(@"%@", elementName);
    if ([elementName isEqualToString:@"contect"]) {
        self.peo = [[People alloc] init];
        self.peo.aId = attributeDict[@"id"];
    }else if ([elementName isEqualToString:@"name"]) {
        self.isNeedEle = YES;
    }else if ([elementName isEqualToString:@"telephone"]){
        self.isNeedEle = YES;
    }
}

/// 找到元素
- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string {
    if (self.isNeedEle) {
        if (self.mstr) {
            [self.mstr appendString:string];
        }else {
            self.mstr = [NSMutableString stringWithFormat:@"%@", string];
        }
    }
    NSLog(@"%@", string);
}

/// 结束的元素
- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(nullable NSString *)namespaceURI qualifiedName:(nullable NSString *)qName {
    NSString *str = [self.mstr stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
    [self.mstr setString:@""];
    if ([elementName isEqualToString:@"name"]) {
        _peo.name = str;
    }else if ([elementName isEqualToString:@"telephone"]){
        _peo.telephone = str;
    }else if ([elementName isEqualToString:@"contect"]) {
        [self.marr addObject:self.peo];
    }
    self.isNeedEle = NO;
    NSLog(@"%@", elementName);
}

///
- (void)parserDidEndDocument:(NSXMLParser *)parser {
    NSLog(@"结束解析");
    NSLog(@"%@", self.marr);
}

 DOM解析 (Document Object Model) 第三方解析 GDataXMLNode  全部读入。占用内存，时间长，但是可以把XML文件在内存中构建属性结构，可以遍历和修改节点。

1：导入GDataXMLNode之后会报错，根据提示修改即可

1 // libxml includes require that the target Header Search Paths contain
2 //  Targets -> Build Settings -> 搜索Header Search Paths 添加
3 //   /usr/include/libxml2
4 //  Targets -> Build Settings -> 搜索Other Linker Flags 添加
5 // and Other Linker Flags contain
6 //
7 //   -lxml2
    // 下载地址 https://github.com/graetzer/GDataXML-HTML
    //GDataXMLNode解析方式 使用的是 DOM（Document Object Model）
    NSString *path = [[NSBundle mainBundle] pathForResource:@"aa" ofType:@"xml"];
    NSData *data = [NSData dataWithContentsOfFile:path];
    GDataXMLDocument *doc = [[GDataXMLDocument alloc] initWithData:data error:nil];
    NSArray<GDataXMLElement *> *arr = [doc.rootElement elementsForName:@"contect"];
    self.marr = [@[] mutableCopy];
    for (GDataXMLElement *ele in arr) {
        People *pe = [[People alloc] init];
        /// 获取的下面的节点
        for (GDataXMLNode *node in ele.children) {
            if ([node.name isEqualToString:@"name"]) {
                pe.name = node.stringValue;
            }
            if ([node.name isEqualToString:@"telephone"]) {
                pe.telephone = node.stringValue;
            }
        }
        /// 获取的是属性节点数组
        for (GDataXMLNode *node in ele.attributes) {
            if ([node.name isEqualToString:@"id"]) {
                pe.aId = node.stringValue;
            }
        }
        [self.marr addObject:pe];
    }
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原文地址：https://www.cnblogs.com/jisa/p/9301520.html