ios - 格式字符串不是字符串文字

Question

行中有错误 totalSelection=[[NSString alloc] initWithFormat:dataView.text];错误提示 Format string is not literal，这是什么意思？

- (void)viewDidLoad {
     clientName= [[NSArray alloc] initWithObjects:@"Bob",@"Pete",@"Julie",@"Stacey",@"Eric", nil];
     anteCedent= [[NSArray alloc] initWithObjects:@"Demand",@"Alone",@"Transition",@"FreePlay",@"Eating", nil];
     problemBx = [[NSArray alloc] initWithObjects:@"Slap",@"Spit",@"Bite",@"Pinch",@"Threat", nil];
     conSequence= [[NSArray alloc] initWithObjects:@"Attention",@"Ignored",@"Escape",@"Tangible",@"Redirected", nil];
     [super viewDidLoad];
}

-(NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView{
    return componentCount;
}


//The layout of the picker view has been outlined and app can interpret the code

-(NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:   (NSInteger)component{
    if (component==clientComponent){
        return [clientName count];
    }
    if (component== bxComponent){
        return [problemBx count];
    }

    if (component== antComponent){
        return [anteCedent count];
    }

    if (component== conComponent){
        return [conSequence count];
    }
}

//Enables the app to correctly identify the number corresponding to each row 
 -(NSString *)pickerView:(UIPickerView*)pickerView titleForRow:(NSInteger)row forComponent: (NSInteger)component{
    if (component==clientComponent){
        return [clientName objectAtIndex:row];
    }
    if (component==bxComponent) {
        return [problemBx objectAtIndex:row];
    }
    if (component==antComponent) {
        return [anteCedent objectAtIndex:row];
    }
    if (component==conComponent){
        return [conSequence objectAtIndex:row];
    }
}

-(void)pickerView:(UIPickerView*)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger) component{
    NSString *Clientmessage;
    NSString *BXmessage;
    NSString *anteMessage;
    NSString *conMessage;
    if (component==clientComponent){
        Clientmessage=[[NSString alloc] initWithFormat:@"%@",[clientName objectAtIndex:row]];
        lblClient.text=Clientmessage;
    }
    if (component==bxComponent){
        BXmessage=[[NSString alloc] initWithFormat:@"%@",[clientName objectAtIndex:row]];
        lblBX.text=BXmessage;
    }
    if (component==antComponent){
        anteMessage=[[NSString alloc] initWithFormat:@"%@",[clientName objectAtIndex:row]];
        lblAnte.text=anteMessage;
    }
    if (component==conComponent){
        conMessage=[[NSString alloc] initWithFormat:@"%@",[clientName objectAtIndex:row]];
        lblBX.text=conMessage;
    }
}

//Set the time and date and adding information
-(IBAction)EnterSelection:(id)sender;{
    NSString *totalSelection;
    NSDate *date1 = [NSDate date];
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setDateFormat:@"YYYY-MM-dd HH:mm:ss"];
    NSString *myDate = [dateFormatter stringFromDate:date1];
    totalSelection=[[NSString alloc] initWithFormat:dataView.text];
    totalSelection=[totalSelection stringByAppendingString:@"\n"];
    totalSelection=[totalSelection stringByAppendingString:lblClient.text];
    totalSelection=[totalSelection stringByAppendingString:@","];
    totalSelection=[totalSelection stringByAppendingString:lblAnte.text];
    totalSelection=[totalSelection stringByAppendingString:@","];
    totalSelection=[totalSelection stringByAppendingString:lblBX.text];
    totalSelection=[totalSelection stringByAppendingString:@","];
    totalSelection=[totalSelection stringByAppendingString:lblCon.text];
    totalSelection=[totalSelection stringByAppendingString:@","];
    totalSelection=[totalSelection stringByAppendingString:myDate];
    dataView.text=totalSelection;
}

//sets the code that will automatically enetered as the recipient of the email
-(void) send:(id) sender{
    txtTo=@"YourEmail@yahoo.com";
    txtSubject=@"ABC Data";
    [self sendEmailTo:txtTo withSubject:txtSubject withBody:[dataView text]];
}

//Organizes all email info and calls up mail function of iPhone
-(void) sendEmailTo: (NSString*)to withSubject:(NSString*)subject withBody:(NSString*)body {
    txtTo=@"YourEmail@yahoo.com";
    txtSubject=@"ABC Data";
    NSString *mailString= [NSString stringWithFormat:@"mailto:ff?to=%@&subject=%@&body=%@",
        [to stringByAddingPercentEscapesUsingEncoding:NSASCIIStringEncoding],
        [subject stringByAddingPercentEscapesUsingEncoding:NSASCIIStringEncoding],
        [body stringByAddingPercentEscapesUsingEncoding:NSASCIIStringEncoding]];

    [[UIApplication sharedApplication] openURL:[NSURL URLWithString:mailString]];
}

// Do any additional setup after loading the view, typically from a nib.

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

Answer 1

如果 dataView.text 包含 % 怎么办？然后 initWithFormat: 会将其解释为格式规范的开始，并(可能)尝试查看您未在消息中传递的参数。您可能会崩溃或损坏数据。这种类型的错误是如此常见和严重，以至于编译器被编程为检测风险并向您发出警告。

因为您不想使用 dataView.text 作为格式字符串，所以不要将它传递给 initWithFormat:。该行最好这样写:

  totalSelection = [dataView.text copy];

您甚至可以像这样重写整个字符串附加部分:

  totalSelection = [dataView.text stringByAppendingString:@"\n"];
  NSString *fields = [@[
      lblClient.text, lblAnte.text, lblBX.text, lblCon.text, myDate
  ] componentsJoinedByString:@","];
  totalSelection = [totalSelection stringByAppendingString:fields];