自定义类 WMSTileOverlayUtil，继承自高德地图接口 MATileOverlay，主要重载函数： 
- (NSURL *)URLForTilePath:(MATileOverlayPath)path; 
- (void)loadTileAtPath:(MATileOverlayPath)path result:(void (^)(NSData *tileData, NSError *error))result;，见代码注释。

#import <Foundation/Foundation.h>
#import <MAMapKit/MATileOverlay.h>


@interface WMSTileOverlayUtil : MATileOverlay

- (id)initWithRootURL:(NSString *)rootRUL;

/**
 * @brief 以tile path生成URL。用于加载tile,此方法默认填充URLTemplate
 * @param path tile path
 * @return 以tile path生成tileOverlay
 */
- (NSURL *)URLForTilePath:(MATileOverlayPath)path;

@end

#import "WMSTileOverlayUtil.h"
#import <MAMapKit/MAMapKit.h>
#import <AMapFoundationKit/AMapFoundationKit.h>
#import <math.h>

#import "Api.h"

@implementation WMSTileOverlayUtil
{
    NSString *  rootURL;
    NSInteger   titleSize;           // = 256
    double      initialResolution;   // = 156543.03392804062;//2*Math.PI*6378137/titleSize;
    double      originShift;         // = 20037508.342789244;//2*Math.PI*6378137/2.0; 周长的一半
    double      HALF_PI;             // = Math.PI / 2.0;
    double      RAD_PER_DEGREE;      // = Math.PI / 180.0;
    double      METER_PER_DEGREE;    // = originShift / 180.0;//一度多少米
    double      DEGREE_PER_METER;    // = 180.0 / originShift;//一米多少度
}

- (id)initWithRootURL:(NSString *)rootRUL {
    self = [super init];
    if (self) {
        rootURL = rootRUL;
        titleSize = 256;
        initialResolution = 156543.03392804062;
        originShift = 20037508.342789244;
        HALF_PI = M_PI_2;
        RAD_PER_DEGREE = M_PI / 180.0;
        METER_PER_DEGREE = originShift / 180.0;
        DEGREE_PER_METER = 180.0 / originShift;
    }
    return self;
}

/**
 * @brief 以tile path生成URL。用于加载tile,此方法默认填充URLTemplate
 * @param path tile path
 * @return 以tile path生成tileOverlay
 */
- (NSURL *)URLForTilePath:(MATileOverlayPath)path {
    NSString * strURL = [[NSString alloc] initWithFormat:@"%@%@", rootURL, [self titleBoundsByX:path.x
                                                                                              Y:path.y
                                                                                              Z:path.z]];
    NSURL * url = [NSURL URLWithString:strURL];
    return url;
}

/**
 * @brief 加载被请求的tile,并以tile数据或加载tile失败error访问回调block;默认实现为首先用URLForTilePath去获取URL,然后用异步NSURLConnection加载tile
 * @param path   tile path
 * @param result 用来传入tile数据或加载tile失败的error访问的回调block
 */
- (void)loadTileAtPath:(MATileOverlayPath)path result:(void (^)(NSData *tileData, NSError *error))result {
    if (path.z < 8) return;
    NSURL * url = [self URLForTilePath:path];
    NSString * strURL = url.absoluteString;

    SuccessCallback successCallback = ^(id responseObject) {
        UIImage * image = [UIImage imageWithData:responseObject];
        NSData * data = UIImagePNGRepresentation(image);
        result(data, nil);
    };

    FailureCallBack failureCallBack = ^(NSError *error) {
        result(nil, error);
    };

    [Api GETWMSWith:strURL successCallback:successCallback failureCallBack:failureCallBack];
}

/**
 * @brief 取消请求瓦片，当地图显示区域发生变化时，会取消显示区域外的瓦片的下载, 当disableOffScreenTileLoading=YES时会被调用。since 5.3.0
 * @param path  tile path
 */
- (void)cancelLoadOfTileAtPath:(MATileOverlayPath)path {
    [super cancelLoadOfTileAtPath:path];
}

/**
 * 根据瓦片的x/y等级返回瓦片范围
 *
 * @param tx x
 * @param ty y
 * @param zoom z
 * @return url
 */
- (NSString *)titleBoundsByX:(NSInteger)tx Y:(NSInteger)ty Z:(NSInteger)zoom {
    double minX = [self pixels2Meters:(tx * titleSize) zoom:zoom];
    double maxY = -[self pixels2Meters:(ty * titleSize) zoom:zoom];
    double maxX = [self pixels2Meters:((tx + 1) * titleSize) zoom:zoom];
    double minY = -[self pixels2Meters:((ty + 1) * titleSize) zoom:zoom];

    //转换成经纬度
    minX = [self meters2Lon:minX];
    minY = [self meters2Lat:minY];
    maxX = [self meters2Lon:maxX];
    maxY = [self meters2Lat:maxY];
    //坐标转换工具类构造方法 Gps( WGS-84) 转 为高德地图需要的坐标
    CLLocationCoordinate2D amapcoord = AMapCoordinateConvert(CLLocationCoordinate2DMake(minY, minX), AMapCoordinateTypeGPS);
    minY = amapcoord.latitude;
    minX = amapcoord.longitude;

    CLLocationCoordinate2D maxAmapcoord = AMapCoordinateConvert(CLLocationCoordinate2DMake(maxY, maxX), AMapCoordinateTypeGPS);
    maxY = maxAmapcoord.latitude;
    maxX = maxAmapcoord.longitude;
    NSString * result = [[NSString alloc] initWithFormat:@"%f,%f,%f,%f&width=256&height=256", minX, minY, maxX, maxY];
    return result;
}

/**
 * 根据像素、等级算出坐标
 *
 * @param p p
 * @param zoom z
 * @return double
 */
- (double)pixels2Meters:(NSInteger)p zoom:(NSInteger)zoom {
    return p * [self resolution:zoom] - originShift;
}

/**
 * 计算分辨率
 *
 * @param zoom z
 * @return double
 */
- (double)resolution:(NSInteger)zoom {
    return initialResolution / (pow(2, zoom));
}

/**
 * X米转经纬度
 */
- (double)meters2Lon:(double)mx {
    double lon = mx * DEGREE_PER_METER;
    return lon;
}

/**
 * Y米转经纬度
 */
- (double)meters2Lat:(double)my {
    double lat = my * DEGREE_PER_METER;
    lat = 180.0 / M_PI * (2 * atan(exp(lat * RAD_PER_DEGREE)) - HALF_PI);
    return lat;
}

@end

其中，- (void)loadTileAtPath:(MATileOverlayPath)path result:(void (^)(NSData *tileData, NSError *error))result; 函数中，使用自己写的 网络访问层去请求 wms 服务，并通过 result 函数贴到地图上。你也可以 改写成自己的网络访问层。

问题

为啥要重载 - (void)loadTileAtPath:(MATileOverlayPath)path result:(void (^)(NSData *tileData, NSError *error))result; 函数，因为只是从载 - (NSURL *)URLForTilePath:(MATileOverlayPath)path; 生成 NSURL 后，loadTileAtPath 函数会去通过网络请求加载 wms 服务，然而，这一步网络请求会报错：NSURLConnection -errorcode -1004，且一个星期没有解决为啥报错，所以只得重写，如果有熟悉高德地图 api 的小伙伴能够给予解答，不胜感激。

注意

如果使用 AFNetworking 要注意修改支持的类型：

 AFHTTPSessionManager * manager = [[AFHTTPSessionManager alloc] init];
 AFHTTPResponseSerializer *serializer=[AFHTTPResponseSerializer serializer];
 serializer.acceptableContentTypes = [NSSet setWithObject:@"image/png"];
 manager.responseSerializer = serializer;