IOS 火星坐标转凯立德K码

+(NSString *) EncodeLat:(double)lat lon:(double)lon {
    
    lat = lat * 1000000;
    lon = lon * 1000000;
    
    NSString *k;
    
    lon -= 70000000;
    lat -= 5000000;
    
    if (lat > 35000000){
        if (lon <= 35000000) {
            k = @"6";
        } else {
            k = @"5";
        }
    }else
        if (lon <= 35000000) {
            k = @"7";
        }else {
            k = @"8";
        }
    
    if (lon > 35000000) {
        lon -= 35000000;
    }
    if (lat > 35000000) {
        lat -= 35000000;
    }
    k = [k stringByAppendingString:[self encode:lon]];
    k = [k stringByAppendingString:[self encode:lat]];
    return k;
}
+(NSString *)encode:(double)v {
    
    NSString *codes = @"0123456789abcdefghijkmnpqrstuvwxyz";
    
    NSString *pch = @"";
    v = v * 9 / 250;
    
    for (int i = 0; i < 4; ++i) {
        
        int location = abs((int)v%34);
        NSString *str = [codes substringWithRange:NSMakeRange(location, 1)];
        //NSString *str = [NSString stringWithFormat:@"%d",[codes characterAtIndex:(int)v%34]];
        
        pch = [pch stringByAppendingString:str];
        v /= 34;
    }
    return pch;
}