1、採用第三方函式庫上傳檔案到ftp時總報錯
2、程式碼：

    static NSString * const FTP_ADDRESS = @"ftp://54.223.34.111:21/";
    static NSString * const USERNAME = @"123456";
    static NSString * const PASSWORD = @"123456";

    
    LxFTPRequest * request = [LxFTPRequest uploadRequest];
    request.serverURL = [[NSURL URLWithString:FTP_ADDRESS]URLByAppendingPathComponent:@"./test.txt"];
    request.localFileURL = [NSURL fileURLWithPath:fileName];
    request.username = USERNAME;
    request.password = PASSWORD;
    request.progressAction = ^(NSInteger totalSize, NSInteger finishedSize, CGFloat finishedPercent) {
        
    };
    request.successAction = ^(Class resultClass, id result) {
        NSLog(@"uploadbyftp success");
    };
    request.failAction = ^(CFStreamErrorDomain domain, NSInteger error, NSString * errorMessage) {
        NSLog(@"domain = %ld, error = %ld, errorMessage = %@", domain, error, errorMessage);    // domain = 1, error = 49, errorMessage = Unknown
    };
    [request start];

總輸出錯誤：domain = 1, error = 49, errorMessage = Unknown
其中，domain=1為：

typedef CF_ENUM(CFIndex, CFStreamErrorDomain) {
    kCFStreamErrorDomainCustom = -1L,      /* custom to the kind of stream in question */
    kCFStreamErrorDomainPOSIX = 1,        /* POSIX errno; interpret using <sys/errno.h> */
    kCFStreamErrorDomainMacOSStatus      /* OSStatus type from Carbon APIs; interpret using <MacTypes.h> */
};

error=49為：#define EADDRNOTAVAIL 49 / Can't assign requested address /

本地待上傳檔案為：@"/var/mobile/Containers/Data/Application/2C632403-AC9C-4250-8E43-0CC0EAC14272/Library/Caches/CrashLog/iPhone_1.0.0.0_udid_201605236376037036370363633003363303633033033件30.