Question

我正在尝试将NSSting称为void方法，但我得到 EXC_BAD_ACCESS错误。会导致这种情况的原因是什么？

我在btnPickerDoneTouchHandler中为NSLog做了一个刹车点（调试），但是choiceList是空的。

·H

@interface controlView : UIViewController{
      NSString *choiceList;
}

.M：

-(NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView{

    return 1;
}

-(NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component{

    return [res count];
}



-(NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component{

    return [[res objectAtIndex:row]objectForKey:@"choice_name"];   
}

- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component
{
      choiceList = [NSString stringWithFormat:@"<r_PM act='closepos_choice' cl_choice='%d'/>", row];

      NSLog(@"You have selected row %@", choiceList);
}


- (void)btnPickerDoneTouchHandler{
      //I have put here the brakepoint.
      NSLog(@"choiceList is %@", choiceList);
}

Answer 1

试试这个 -

在你的.h文件中

@property (strong, nonatomic) NSString  * choiceList;

在你的.m文件中

@synthesize choiceList;

- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component
{
  self.choiceList = [NSString stringWithFormat:@"<r_PM act='closepos_choice' cl_choice='%d'/>", row];

  NSLog(@"You have selected row %@", self.choiceList);
}


- (void)btnPickerDoneTouchHandler{
    //I have put here the brakepoint.
    NSLog(@"choiceList is %@", self.choiceList);
}

Answer 2

您可以执行以下操作：

·H：

@interface controlView : UIViewController 
@property (strong, nonatomic) NSString  * choiceList;

.M：

- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component
{
      self.choiceList = [NSString stringWithFormat:@"<r_PM act='closepos_choice' cl_choice='%d'/>", row];

      NSLog(@"You have selected row %@", choiceList);
}


- (void)btnPickerDoneTouchHandler{
      //I have put here the brakepoint.
      NSLog(@"choiceList is %@", self.choiceList);
}

或

您需要alloc您的字符串才能在课程中访问它：

choiceList = [[NSString alloc]initWithString:@"<r_PM act='closepos_choice' cl_choice='%d'/>", row];

Answer 3

只需在.h文件中创建 @property ，例如

@property (strong, nonatomic) NSString  * choiceList;

在另一个void方法问题中调用NSString

3 个答案: