我正在尝试通过蓝牙 4.0 LE 将 .png 图像文件从一台 iOS 设备发送到另一台设备。
我能够处理简单的数据，如字符串，但无法成功发送和利用图像文件。
在外围设备中，我从这个开始
pictureBeforeData = [UIImage imageNamed:@"myImage.png"];
NSData *myData = UIImagePNGRepresentation(pictureBeforeData);
然后我制作myData一个特征值。
_myCharacteristic =
[[CBMutableCharacteristic alloc] initWithType:_myCharacteristicUUID
properties:CBCharacteristicPropertyRead
value:myData
permissions:CBAttributePermissionsReadable];
在中央设备中，当特征值更新时我有这个
- (void)peripheral:(CBPeripheral *)peripheral didUpdateValueForCharacteristic:(CBCharacteristic *)characteristic error:(NSError *)error {
if ([characteristic.UUID isEqual:[CBUUID UUIDWithString:_myCharacteristicUUID]]) {
NSLog(@"PICTURE CHARACTERISTIC FOUND"); // This successfully gets logged
NSData *dataFromCharacteristic = [[NSData alloc] initWithData:characteristic.value];
UIImage *imageFromData = [[UIImage alloc]initWithData:dataFromCharacteristic];
// This correctly logs the size of my image
NSLog(@"SIZE: %f, %f", imageFromData.size.height, imageFromData.size.width);
// This causes the imageView to turn completely black
_sentPictureImageView.image = imageFromData;
if (!([_myImagesArray containsObject:imageFromData]))
{
NSLog(@"DOES NOT CONTAIN"); // This is successfully logged
[_myImagesArray addObject:imageFromData]; // This runs but is apparently not adding the image to the array
}
NSLog(@"COUNT: %u", _contactsImagesArray.count); // This always logs 0 - The array is empty }
编辑 8-27-13：我能够成功发送单色 1×1 像素 .png 文件，该文件大约 5,600 字节大。我无法发送只有大约 2,000 字节的多色 20×20 像素 .png 文件。我能够发送仅包含一种颜色和更少像素的较大文件，但无法发送包含多种颜色和更多像素的较小文件。
编辑 8-30-13：我绝对必须将数据解析成更小的块。在 Apple 的一个示例项目中，我找到了一种可以做到这一点的方法。我似乎无法确切理解如何在我自己的代码中实现这一点，但我目前正试图弄清楚如何。这是代码：
- (void)sendData {
// First up, check if we're meant to be sending an EOM
static BOOL sendingEOM = NO;
if (sendingEOM) {
// send it
BOOL didSend = [self.peripheralManager updateValue:[@"EOM" dataUsingEncoding:NSUTF8StringEncoding] forCharacteristic:self.transferCharacteristic onSubscribedCentrals:nil];
// Did it send?
if (didSend) {
// It did, so mark it as sent
sendingEOM = NO;
NSLog(@"Sent: EOM");
}
// It didn't send, so we'll exit and wait for peripheralManagerIsReadyToUpdateSubscribers to call sendData again
return;
}
// We're not sending an EOM, so we're sending data
// Is there any left to send?
if (self.sendDataIndex >= self.dataToSend.length) {
// No data left. Do nothing
return;
}
// There's data left, so send until the callback fails, or we're done.
BOOL didSend = YES;
while (didSend) {
// Make the next chunk
// Work out how big it should be
NSInteger amountToSend = self.dataToSend.length - self.sendDataIndex;
// Can't be longer than 20 bytes
if (amountToSend > NOTIFY_MTU) amountToSend = NOTIFY_MTU;
// Copy out the data we want
NSData *chunk = [NSData dataWithBytes:self.dataToSend.bytes+self.sendDataIndex length:amountToSend];
// Send it
didSend = [self.peripheralManager updateValue:chunk forCharacteristic:self.transferCharacteristic onSubscribedCentrals:nil];
// If it didn't work, drop out and wait for the callback
if (!didSend) {
return;
}
NSString *stringFromData = [[NSString alloc] initWithData:chunk encoding:NSUTF8StringEncoding];
NSLog(@"Sent: %@", stringFromData);
// It did send, so update our index
self.sendDataIndex += amountToSend;
// Was it the last one?
if (self.sendDataIndex >= self.dataToSend.length) {
// It was - send an EOM
// Set this so if the send fails, we'll send it next time
sendingEOM = YES;
// Send it
BOOL eomSent = [self.peripheralManager updateValue:[@"EOM" dataUsingEncoding:NSUTF8StringEncoding] forCharacteristic:self.transferCharacteristic onSubscribedCentrals:nil];
if (eomSent) {
// It sent, we're all done
sendingEOM = NO;
NSLog(@"Sent: EOM");
}
return;
}
}}
我imageView的是黑色方块，它应该显示我发送过来的图像。
