Question

如果之前有人问过，我道歉我发送一个包含大约750字节的长字符串，从iOS设备到蓝牙热敏打印机。但是，当打印出字符串时，打印机仅打印出CChar中大约160字节的部分上下文。我有点困惑为什么会发生这种情况，有人可以解释一下吗？

代码：

    <div class="table-responsive">
        <table id="basic-table" class="data-table table table-striped nowrap table-hover" cellspacing="0" width="100%">
            <thead>
                <tr>
                    <th>{{'Plate'|translate}}</th>
                    <th>{{'Driver Name'|translate}}</th>
                    <th>{{'Start Time'|translate}}</th>
                    <th>{{'Starting Address'|translate}}</th>
                    <th>{{'End Time'|translate}}</th>
                    <th>{{'Ending Address'|translate}}</th>
                    <th>{{'Work Duration'|translate}}</th>
                    <th>{{'Distance'|translate}}</th>
                </tr>
            </thead>
            <tbody>
                <tr *ngFor="let item of workDataReportList">
                    <td>{{item.Name}}</td>
                    <td>{{item.DriverName}}</td>
                    <td>{{item.StartTime | date:'dd.MM.yy hh:mm'}}</td>
                    <td>{{item.StartAddress}}</td>
                    <td>{{item.EndTime | date:'dd.MM.yy hh:mm'}}</td>
                    <td>{{item.EndAddress}}</td>
                    <td>{{item.RunningTime}}</td>
                    <td>{{item.Km | distance}}</td>
                </tr>
            </tbody>
        </table>
    </div>
</div>

在writeValue函数中

let cfEnc = CFStringEncodings.GB_18030_2000
let enc = CFStringConvertEncodingToNSStringEncoding(CFStringEncoding(cfEnc.rawValue))

let ccc = "The franchise began in 1977 with the release of the film Star Wars 
    (subtitled Episode IV: A New Hope in 1981[2][3]), which became a worldwide pop 
    culture phenomenon. It was followed by the successful sequels The Empire 
    Strikes Back (1980) and Return of the Jedi (1983); these three films constitute 
    the original Star Wars trilogy. A prequel trilogy was released between 1999 and 
    2005, which received mixed reactions. A sequel trilogy began in 2015 with the 
    release of Star Wars: The Force Awakens. All seven films were nominated for 
    Academy Awards (with wins going to the first two films) and have been 
    commercial successes, with a combined box office revenue of $7.471 billion,[4] 
    making Star Wars the third highest-grossing film series.[5] Spin-off films 
    include Star Wars: The Clone Wars (2008) and Rogue One (2016), which is the 
    first in an upcoming series of anthology films.\n\nThe series has spawned an 
    extensive media franchise—the Star Wars expanded universe—including books, 
    television series, computer and video games, and comic books, resulting in 
    significant development of the series's fictional universe. Star Wars also 
    holds a Guinness World Records title for the \"Most successful film 
    merchandising franchise. In 2015, the total value of the Star Wars franchise 
    was estimated at USD $41.9 billion,[6] making Star Wars the second highest-
    grossing media franchise of all time.\n\nIn 2012, The Walt Disney Company 
    acquired Lucasfilm for $4.06 billion and earned the distribution rights to all 
    subsequent Star Wars films, beginning with the release of The Force Awakens in 
    2015.[7] The former distributor, 20th Century Fox, retains the physical 
    distribution rights to the first two Star Wars trilogies, owning permanent 
    rights for the original 1977 film and holding the rights to Episodes I–III, V, 
    and VI until May 2020.[8][9] Walt Disney Studios owns digital distribution 
    rights to all the Star Wars films, excluding A New Hope."
print(ccc.lengthOfBytes(using: String.Encoding(rawValue: enc))) //count number is 164           

if let data = ccc.data(using: String.Encoding(rawValue: enc)) {
    self.writeValue(data)
}

我是否必须切断字符串才能使其正常工作？

蓝牙LE：从iOS发送数据缩短了

0 个答案: