本文主要是講一下我們?cè)谡?qǐng)求網(wǎng)絡(luò)的時(shí)候如何去配置相關(guān)的參數(shù)然后成功得到響應(yīng)。那本文以請(qǐng)求百度的API中圖像識(shí)別為例來(lái)說(shuō)一下該如何去配置庶香。

目的需求

我需要把一張包含二維碼的圖片通過(guò)百度的圖像識(shí)別接口來(lái)判定是否包含二維碼。

準(zhǔn)備工作

1>裝有Xcode的MAC電腦一臺(tái)
2>準(zhǔn)備一張二維碼圖片染服，這個(gè)隨便找一張枫甲，或者去草料二維碼制作一張也是OK的
3>百度云登錄注冊(cè)，并創(chuàng)建一個(gè)圖像識(shí)別應(yīng)用副瀑，拿到API Key和Secret Key
4>百度對(duì)接文檔：圖像審核組合接口

開(kāi)始對(duì)接

1>創(chuàng)建工程項(xiàng)目，然后創(chuàng)建一個(gè)網(wǎng)絡(luò)請(qǐng)求恋谭。那么此處我選擇AFN糠睡，并且是手動(dòng)導(dǎo)入框架。首先這個(gè)過(guò)程是要先通過(guò)API Key和Secret Key獲取AccessToken,然后再通過(guò)AccessToken再將圖片通過(guò)POST請(qǐng)求發(fā)送給百度鑒別疚颊，然后返回結(jié)果狈孔。

Snip20170812_28.png

獲取AccessToken的代碼：

- (void)viewDidLoad {
    [super viewDidLoad];
     
    [self addBtn];
}

- (void)addBtn{
    UIButton *btn = [[UIButton alloc]init];
    btn.frame = CGRectMake(0, 300, 200, 50);
    CGFloat btnCenterX = self.view.center.x;
    CGFloat btnCenterY = btn.frame.origin.y + btn.frame.size.height * 0.5;
    CGPoint btnCenter = CGPointMake(btnCenterX, btnCenterY);
    btn.center = btnCenter;
    btn.backgroundColor = [UIColor orangeColor];
    [self.view addSubview:btn];
    [btn setTitle:@"點(diǎn)我獲取Token" forState:UIControlStateNormal];
    [btn addTarget:self action:@selector(didClickBtn) forControlEvents:UIControlEventTouchUpInside];
}

- (void)didClickBtn{
    [self getAccessToken];
}

- (void)getAccessToken{
    AFHTTPSessionManager *manager = [AFHTTPSessionManager manager];
    //一但用了這個(gè)返回的那個(gè)responseObject就是NSData，如果不用就是簡(jiǎn)單的
    //manager.responseSerializer = [AFHTTPResponseSerializer serializer];
    //manager.requestSerializer = [AFJSONRequestSerializer serializer];
    manager.responseSerializer.acceptableContentTypes = [NSSet setWithObjects:@"application/json", @"text/json", @"text/javascript", @"text/html",@"image/jpeg",@"text/plain", nil];
    NSDictionary *dict = @{
                           @"grant_type":@"client_credentials",
                           @"client_id":@"填寫(xiě)你的API Key",
                           @"client_secret":@"填寫(xiě)你的Secret Key"
                           };
    [manager POST:@"https://aip.baidubce.com/oauth/2.0/token" parameters:dict progress:nil success:
     ^(NSURLSessionDataTask * _Nonnull task, id  _Nullable responseObject) {
         /*
         if ([responseObject isKindOfClass:[NSData class]]) {
             NSError *error;
             id object = [NSJSONSerialization JSONObjectWithData:responseObject options:0 error:&error];
             NSLog(@"%@",object);
         }
         if (![responseObject isKindOfClass:[NSDictionary class]]) {
             NSLog(@"不是想要的結(jié)果材义，應(yīng)該是哪里出錯(cuò)了均抽，請(qǐng)注意檢查！");
             NSLog(@"responseObject = %@",responseObject);
             return;
         }
        */
         NSDictionary *dict = (NSDictionary *)responseObject;
         
         NSString *accessToken = dict[@"access_token"];
         _accessToken = dict[@"access_token"];
         NSLog(@"%@",accessToken);
         
         //調(diào)用判定二維碼的接口
         [self getResultOfQRImageWithAFN1];
         //[self getResultOfQRImageWithAFN2];
         //[self getResultOfQRImageWithNSURLSession];
         
     } failure:^(NSURLSessionDataTask * _Nullable task, NSError * _Nonnull error) {
         NSLog(@"請(qǐng)求失敗--%@",error);
     }];
}

PS :注意以下有一點(diǎn)要說(shuō)一下
下面這句代碼意思是得到的響應(yīng)會(huì)序列化其掂，何為序列化油挥，序列化就是將其他的數(shù)據(jù)類型轉(zhuǎn)成二進(jìn)制，所以一旦我們加上了這句話款熬，那么我們?cè)诮邮枕憫?yīng)的時(shí)候深寥，就要反序列化，將二進(jìn)制的NSData轉(zhuǎn)成其他響應(yīng)的數(shù)據(jù)類型

manager.responseSerializer = [AFHTTPResponseSerializer serializer];

2>獲取AccessToken之后就需要去請(qǐng)求圖像識(shí)別接口了

Snip20170812_26.png

Snip20170812_27.png

Snip20170812_29.png

首先請(qǐng)求是POST贤牛，我們?cè)僬f(shuō)下以下幾個(gè)要點(diǎn)：
要點(diǎn)一：
參數(shù)中有URL參數(shù)惋鹅，那么這個(gè)URL參數(shù)是直接拼接在URL后面的，這個(gè)要注意
要點(diǎn)二：
其中說(shuō)到的Header表示的是我們傳給百度接口的是內(nèi)容Content-Type是Json格式的殉簸，并且是UTF-8編碼格式的闰集，所以這個(gè)要特別注意，很多請(qǐng)求失敗可能是這些設(shè)置沒(méi)有設(shè)置好才導(dǎo)致的application/json;charset=utf-8
要點(diǎn)三：
請(qǐng)求體應(yīng)該怎么放般卑，在AFN中如果是使用POST的URL方式的接口中的parameters這個(gè)參數(shù)其實(shí)就是請(qǐng)求體武鲁，并且這是id類型的，只要我們?cè)O(shè)置好請(qǐng)求的內(nèi)容格式然后這個(gè)參數(shù)傳入對(duì)應(yīng)格式的內(nèi)容即可

PS: 這里面就涉及到請(qǐng)求體蝠检，那怎么設(shè)置請(qǐng)求體呢在AFN中洞坑，有以下的三種方式：

方式一：

//這個(gè)是用Request方式
- (void)getResultOfQRImageWithAFN1{
    
    //由于是POST，將一些憑證如AccessToken之類的拼接在一起蝇率，這種叫URL參數(shù)迟杂，同GET一樣
    NSString *urlString = @"https://aip.baidubce.com/api/v1/solution/direct/img_censor";
    NSString *newURLString = [NSString stringWithFormat:@"%@?access_token=%@?",urlString,_accessToken];
    NSURL *url = [NSURL URLWithString:newURLString];
    //創(chuàng)建請(qǐng)求request
    NSMutableURLRequest *request =[NSMutableURLRequest requestWithURL:url cachePolicy:0 timeoutInterval:30];
    //設(shè)置請(qǐng)求方式為POST
    request.HTTPMethod = @"POST";
    //設(shè)置請(qǐng)求內(nèi)容格式
    [request setValue:@"application/json;charset=utf-8" forHTTPHeaderField:@"Content-Type"];
    //設(shè)置請(qǐng)求體參數(shù)
    NSString *base64String = [self base64EncodeImageWithName:@"qrcode"];
    NSArray *array = @[@"watermark"];
    NSDictionary *params = @{@"image":base64String,
                             @"scenes": array};
    //這是設(shè)置請(qǐng)求體刽沾，把參數(shù)放進(jìn)請(qǐng)求體(這部分的參數(shù)也叫請(qǐng)求參數(shù))
    NSString *paramJsonStr = [KODJsonService dictionaryToJson:params];
    NSLog(@"paramString = %@",paramJsonStr);
    NSData *data = [paramJsonStr dataUsingEncoding:NSUTF8StringEncoding];
    NSLog(@"data = %@",data);
    request.HTTPBody = [paramJsonStr dataUsingEncoding:NSUTF8StringEncoding];
    
    AFHTTPSessionManager *manager = [AFHTTPSessionManager manager];
    manager.responseSerializer.acceptableContentTypes = [NSSet setWithObjects:@"application/json", @"text/json", @"text/javascript", @"text/html",@"image/jpeg",@"text/plain", nil];
    [[manager dataTaskWithRequest:request completionHandler:^(NSURLResponse * _Nonnull response, id  _Nullable responseObject, NSError * _Nullable error) {
        NSLog(@"請(qǐng)求成功---%@---%@",responseObject,[responseObject class]);
        
        if (error) {
            NSLog(@"%@",error);
            return ;
        }
        NSDictionary *dict = (NSDictionary *)responseObject;
        //以下結(jié)構(gòu)沒(méi)做放空處理，只為了盡快看到效果排拷，請(qǐng)大家自行處理下
        NSDictionary *resultDict = dict[@"result"];
        if (!resultDict) {
            NSLog(@"result沒(méi)有值侧漓，很抱歉，估計(jì)錯(cuò)誤了监氢！");
            return;
        }
        NSDictionary *newDict = resultDict[@"watermark"];
        NSArray *resultArray = newDict[@"result"];
        for (NSDictionary *dict in resultArray) {
            if ([dict[@"type"] isEqualToString:@"QR code"]) {
                NSLog(@"這絕壁有一張二維碼２颊帷！浪腐！");
            }
        }
    }] resume];
}

PS: 這種方式是用manager直接通過(guò)request的方式去請(qǐng)求而不是設(shè)置URL的方式纵揍，另外request是可以設(shè)置HTTPBody的，這樣更加的清晰

方式二：

//這個(gè)是用URL方式的
- (void)getResultOfQRImageWithAFN2{

    AFHTTPSessionManager *manager = [AFHTTPSessionManager manager];
    //這句話加了之后返回的responseObject就是JSONData了议街，如果不加那就是正常的JSON可以直接轉(zhuǎn)成字典然后操作
    manager.responseSerializer = [AFHTTPResponseSerializer serializer];
    manager.requestSerializer = [AFJSONRequestSerializer serializer];
    [manager.requestSerializer setValue:@"application/json;charset=utf-8" forHTTPHeaderField:@"Content-Type"];
    manager.responseSerializer.acceptableContentTypes = [NSSet setWithObjects:@"application/json", @"text/json", @"text/javascript", @"text/html",@"image/jpeg",@"text/plain", nil];
    NSString *urlString = @"https://aip.baidubce.com/api/v1/solution/direct/img_censor";
    NSString *newURLString = [NSString stringWithFormat:@"%@?access_token=%@?",urlString,_accessToken];
    
    NSString *base64String = [self base64EncodeImageWithName:@"qrcode"];
    NSArray *array = @[@"watermark"];
    NSDictionary *params = @{@"image":base64String,
                             @"scenes": array};
    
    [manager POST:newURLString parameters:params progress:nil success:
     ^(NSURLSessionDataTask * _Nonnull task, id  _Nullable responseObject) {
         NSLog(@"請(qǐng)求成功---%@---%@",responseObject,[responseObject class]);
         NSLog(@"成功Ｔ蠼鳌！特漩！");
         NSError *error;

         id object = [NSJSONSerialization JSONObjectWithData:responseObject options:0 error:&error];
         if ([object isKindOfClass:[NSDictionary class]]) {
             NSDictionary *response = (NSDictionary *)object;
             NSLog(@"%@",response);
             //以下結(jié)構(gòu)沒(méi)做放空處理
             NSDictionary *resultDict = response[@"result"];
             if (!resultDict) {
                 NSLog(@"result沒(méi)有值吧雹，很抱歉，估計(jì)錯(cuò)誤了涂身！");
                 return;
             }
             NSDictionary *newDict = resultDict[@"watermark"];
             NSArray *resultArray = newDict[@"result"];
             for (NSDictionary *dict in resultArray) {
                 if ([dict[@"type"] isEqualToString:@"QR code"]) {
                     NSLog(@"這絕壁有一張二維碼Ｐ劬怼！蛤售！");
                 }
             }
         }
     } failure:^(NSURLSessionDataTask * _Nullable task, NSError * _Nonnull error) {
         NSLog(@"請(qǐng)求失敗--%@",error);
     }];
}

PS: 大家要注意一下以下這兩句代碼的作用,第一句是設(shè)置請(qǐng)求上傳內(nèi)容是Json格式的丁鹉，我試了以下如果單單設(shè)置第二句是會(huì)返回400Bad Request錯(cuò)誤的，如果僅僅設(shè)置第一句是OK的

manager.requestSerializer = [AFJSONRequestSerializer serializer];
    [manager.requestSerializer setValue:@"application/json;charset=utf-8" forHTTPHeaderField:@"Content-Type"];

我看了下AFN的內(nèi)部實(shí)現(xiàn)其實(shí)已經(jīng)設(shè)置好了悴能，大家有興趣可以去查看一下AFN的內(nèi)部源碼

+ (instancetype)serializer {
    return [self serializerWithWritingOptions:(NSJSONWritingOptions)0];
}

+ (instancetype)serializerWithWritingOptions:(NSJSONWritingOptions)writingOptions
{
    AFJSONRequestSerializer *serializer = [[self alloc] init];
    serializer.writingOptions = writingOptions;

    return serializer;
}

最終都會(huì)調(diào)用

- (NSURLRequest *)requestBySerializingRequest:(NSURLRequest *)request
                               withParameters:(id)parameters
                                        error:(NSError *__autoreleasing *)error
{
    NSParameterAssert(request);

    if ([self.HTTPMethodsEncodingParametersInURI containsObject:[[request HTTPMethod] uppercaseString]]) {
        return [super requestBySerializingRequest:request withParameters:parameters error:error];
    }

    NSMutableURLRequest *mutableRequest = [request mutableCopy];

    [self.HTTPRequestHeaders enumerateKeysAndObjectsUsingBlock:^(id field, id value, BOOL * __unused stop) {
        if (![request valueForHTTPHeaderField:field]) {
            [mutableRequest setValue:value forHTTPHeaderField:field];
        }
    }];

    if (parameters) {
        if (![mutableRequest valueForHTTPHeaderField:@"Content-Type"]) {
            [mutableRequest setValue:@"application/json" forHTTPHeaderField:@"Content-Type"];
        }

        [mutableRequest setHTTPBody:[NSJSONSerialization dataWithJSONObject:parameters options:self.writingOptions error:error]];
    }

    return mutableRequest;
}

所以看到這里你會(huì)發(fā)現(xiàn)AFN封裝了好大一圈揣钦，一會(huì)兒在文末貼出純系統(tǒng)NSURLSession怎么實(shí)現(xiàn)

另外有兩個(gè)AFHTTPRequestSerializer的子類,一個(gè)是AFJSONRequestSerializer，這個(gè)是會(huì)把參數(shù)編碼成Json格式搜骡，然后設(shè)置Content-Type為application/json，但是并沒(méi)有進(jìn)行UTF-8編碼佑女，所以這個(gè)還是要注意一下自己編碼

/**
 `AFJSONRequestSerializer` is a subclass of `AFHTTPRequestSerializer` that encodes parameters as JSON using `NSJSONSerialization`, setting the `Content-Type` of the encoded request to `application/json`.
 */
@interface AFJSONRequestSerializer : AFHTTPRequestSerializer

另一個(gè)是AFPropertyListRequestSerializer,這個(gè)可以猜一下记靡，其實(shí)就是XML，并且設(shè)置為application/x-plist

/**
 `AFPropertyListRequestSerializer` is a subclass of `AFHTTPRequestSerializer` that encodes parameters as JSON using `NSPropertyListSerializer`, setting the `Content-Type` of the encoded request to `application/x-plist`.
 */
@interface AFPropertyListRequestSerializer : AFHTTPRequestSerializer

方式三：

- (void)getResultOfQRImageWithAFN3{
    
    AFHTTPSessionManager *manager = [AFHTTPSessionManager manager];
    //這句話加了之后返回的responseObject就是JSONData了团驱，如果不加那就是正常的JSON可以直接轉(zhuǎn)成字典然后操作
    //manager.responseSerializer = [AFHTTPResponseSerializer serializer];
    manager.requestSerializer = [AFJSONRequestSerializer serializer];
    [manager.requestSerializer setValue:@"application/json;charset=utf-8" forHTTPHeaderField:@"Content-Type"];
    manager.responseSerializer.acceptableContentTypes = [NSSet setWithObjects:@"application/json", @"text/json", @"text/javascript", @"text/html",@"image/jpeg",@"text/plain", nil];
    NSString *urlString = @"https://aip.baidubce.com/api/v1/solution/direct/img_censor";
    NSString *newURLString = [NSString stringWithFormat:@"%@?access_token=%@?",urlString,_accessToken];
    
    NSString *base64String = [self base64EncodeImageWithName:@"qrcode"];
    NSArray *array = @[@"watermark"];
    NSDictionary *params = @{@"image":base64String,
                             @"scenes": array};
    NSMutableURLRequest *request = [manager.requestSerializer requestWithMethod:@"POST" URLString:newURLString parameters:params error:nil];
    [[manager dataTaskWithRequest:request completionHandler:^(NSURLResponse * _Nonnull response, id  _Nullable responseObject, NSError * _Nullable error) {
        NSLog(@"%@",error);
        NSLog(@"%@",responseObject);
    }] resume];
}

對(duì)比原生NSURLSession的做法

-(void)getResultOfQRImageWithNSURLSession
{
    NSString *urlString = @"https://aip.baidubce.com/api/v1/solution/direct/img_censor";
    NSString *newURLString = [NSString stringWithFormat:@"%@?access_token=%@?",urlString,_accessToken];
    NSURL *url = [NSURL URLWithString:newURLString];
    NSMutableURLRequest *request =[NSMutableURLRequest requestWithURL:url cachePolicy:0 timeoutInterval:30];
    request.HTTPMethod = @"POST";
    [request setValue:@"application/json;charset=utf-8" forHTTPHeaderField:@"Content-Type"];
    NSString *base64String = [self base64EncodeImageWithName:@"qrcode"];
    NSArray *array = @[@"watermark"];
    NSDictionary *params = @{@"image":base64String,
                             @"scenes": array};
    NSString *paramJsonStr = [KODJsonService dictionaryToJson:params];
    NSLog(@"paramString = %@",paramJsonStr);
    NSData *data = [paramJsonStr dataUsingEncoding:NSUTF8StringEncoding];
    NSLog(@"data = %@",data);
    request.HTTPBody = [paramJsonStr dataUsingEncoding:NSUTF8StringEncoding];
    
    // 3.獲得會(huì)話對(duì)象
    NSURLSession *session = [NSURLSession sharedSession];
    // 4.根據(jù)會(huì)話對(duì)象摸吠，創(chuàng)建一個(gè)Task任務(wù)
    NSURLSessionDataTask *sessionDataTask = [session dataTaskWithRequest:request completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
        //判斷statusCode
        NSHTTPURLResponse *res = (NSHTTPURLResponse *)response;
        if (!(res.statusCode == 200 || error)) {
            NSLog(@"失敗：炕ā４缌　！");
            return;
        }
        NSLog(@"從服務(wù)器獲取到數(shù)據(jù)");
        if (error) {
            NSLog(@"error:%@",error.description);
            return ;
        }
        NSLog(@"%@",data);
        
        NSError *newError;
        id object = [NSJSONSerialization JSONObjectWithData:data options:0 error:&newError];
        if ([object isKindOfClass:[NSDictionary class]]) {
            NSDictionary *response = (NSDictionary *)object;
            NSLog(@"%@",response);
            //這里記得把這個(gè)值取出來(lái)紊选，很深啼止，哈哈哈...
        }
    }];
    //5.最后一步道逗，執(zhí)行任務(wù)，(一定調(diào)用這句話)
    [sessionDataTask resume];
}

附件

其中用到了一個(gè)私有方法：

- (NSString *)base64EncodeImageWithName:(NSString *)name{
    UIImage *image = [UIImage imageNamed:name];
    NSData *data = UIImagePNGRepresentation(image);
    NSData *base64Data = [data base64EncodedDataWithOptions:0];
    NSString *baseString = [[NSString alloc]initWithData:base64Data encoding:NSUTF8StringEncoding];
    
    return baseString;
}

//這是我的一個(gè)工具類里面的方法献烦，大家可以改成對(duì)象方法直接替換調(diào)用即可
+ (NSString*)dictionaryToJson:(NSDictionary *)dic
{
    if (dic.allKeys.count == 0){
#ifdef DSDUBUG
        NSLog(@"%@---%s",self.class,__FUNCTION__);
        NSLog(@"您傳入的字典為空滓窍，無(wú)法轉(zhuǎn)換，請(qǐng)確保字典不為空９恰＠艉弧！");
#endif
        return nil;
    }
    NSError *parseError = nil;
    NSData *jsonData = [NSJSONSerialization dataWithJSONObject:dic options:NSJSONWritingPrettyPrinted error:&parseError];
    return [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
}

圖片：

qrcode.png

文末總結(jié)

其實(shí)今天就講了一個(gè)很重要的問(wèn)題即横，設(shè)置請(qǐng)求體噪生，并且設(shè)置請(qǐng)求的內(nèi)容格式的問(wèn)題。另外一個(gè)是我們其實(shí)可以對(duì)系統(tǒng)的方法NSURLSession進(jìn)行封裝东囚，系統(tǒng)的已經(jīng)很好了跺嗽，其實(shí)有時(shí)間的話我們可以針對(duì)于我們的業(yè)務(wù)自己封裝會(huì)更好，因?yàn)锳FN封裝了一層又一層太繞了...

AFN中的如果是GET請(qǐng)求,用URL方式的那個(gè)接口中的parameters參數(shù)其實(shí)就是我們需要拼接在URL后面的參數(shù)舔庶，所以這個(gè)通常只需要轉(zhuǎn)一下UTF-8就好
AFN中的如果是POST請(qǐng)求,用URL方式的那個(gè)接口中的parameters參數(shù)其實(shí)就是我們需要上傳給后臺(tái)的參數(shù)抛蚁，因?yàn)橐蟼魉孕枰O(shè)置一下內(nèi)容格式，一般上傳是上傳Json惕橙，也有上傳Form表單數(shù)據(jù)的比如圖片等等瞧甩；另外這個(gè)URL參數(shù)就需要跟URL做一下拼接然后整體放置在以下接口中的newURLString：

[manager POST:newURLString parameters:params progress:nil success:
     ^(NSURLSessionDataTask * _Nonnull task, id  _Nullable responseObject) {
//code here...
}];

以上！Ｃ逐小肚逸！