Ios Objective-C dataTaskWithRequest填充变量同步
我在dataTaskWithRequest方面遇到问题,我试图在调用使用dataTaskWithRequest的方法时填充一个变量。但它似乎没有填充,因为当我稍后调用这个变量时,它是nil 方法如下:Ios Objective-C dataTaskWithRequest填充变量同步,ios,objective-c,Ios,Objective C,我在dataTaskWithRequest方面遇到问题,我试图在调用使用dataTaskWithRequest的方法时填充一个变量。但它似乎没有填充,因为当我稍后调用这个变量时,它是nil 方法如下: -(void)deviceCheck:(NSString *)device Completetion:(void (^) (NSArray * result,NSError * error))completion{ NSString *deviceRequestString = [NSSt
-(void)deviceCheck:(NSString *)device Completetion:(void (^) (NSArray * result,NSError * error))completion{
NSString *deviceRequestString = [NSString stringWithFormat:@"%@?device=%@",webservice,device];
NSURL *JSONURL = [NSURL URLWithString:deviceRequestString];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:JSONURL];
NSURLSessionDataTask * dataTask = [[NSURLSession sharedSession] dataTaskWithRequest:request
completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
if(data == nil){
completion(nil,error);
return;
}
NSError *myError;
NSArray *tableArray = [[NSArray alloc]initWithArray:[NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:&myError]];
completion(tableArray,myError);
}];
[dataTask resume];
}
我这样称呼它:
[self deviceCheck:@"testunitid" Completetion:^(NSArray *result, NSError *error) {
if([result count] == 0){
UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"Message" message:@"Device is not valid." preferredStyle:UIAlertControllerStyleAlert];
UIAlertAction* ok = [UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:nil];
[alertController addAction:ok];
[self presentViewController:alertController animated:YES completion:nil];
}else{
scanner=[DTDevices sharedDevice];
[scanner addDelegate:self];
[scanner connect];
Name = [[result objectAtIndex:0] objectForKey:@"name"];
Name = [Name stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
Name = [Name stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLQueryAllowedCharacterSet]];
}
}];
当我将断点放在我能看到的任何地方时,我试图填充变量名,与结果相同,但当我尝试在此处调用它时:
[self getLocationInfo:Name Completetion:^(NSArray *result, NSError *error) {
if([result count] == 0){
UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"Message" message:@"There is an issue with the location tag." preferredStyle:UIAlertControllerStyleAlert];
UIAlertAction* ok = [UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:nil];
[alertController addAction:ok];
[self presentViewController:alertController animated:YES completion:nil];
ScannerMessage.text = @"READY TO SCAN";
ScannerMessage.backgroundColor = [UIColor greenColor];
}else{
[self performSegueWithIdentifier: @"SegueIdentifier" sender: self];
}
}];
零
是否有更好的方法使用dataTaskWithRequest?当我有多个电话时,我发现这种方式有点慢。或者以后是否可以使用变量名?我很困惑。我真的很怀念sendSynchronousRequest,我发现它更快更好。为了避免为零,请确保在两个if-else块中初始化变量:
if([result count] == 0){
Name = @"[result count] == 0";
}else{
//populate names
}
如果[result count]==0
,则必须按照该方向进行调试