我有一个三组件选择器,第三个依赖于前两个。当每个组件中只有3个项目时,这种依赖关系就非常完美。当最终组件中的组件超过三个时(根据其他两个组件的值进行更改,则在尝试移动卷轴时会崩溃)。

收到的错误是“ *由于未捕获的异常'NSRangeException'而终止应用程序,原因:'* -[_ PFArray objectAtIndex:]:超出范围(3)的索引(3)'”

我不知道从哪里得到3的界限。这不是完整的实现,我认为函数可以加载以填充所使用的数组,还可以为按钮提供逻辑以使用按钮按下时的值。如果您认为这些可能是问题,请告诉我。感谢您的任何评论或帮助。谢谢

- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView {
    return 3;
}

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

    NSString *message = [[NSString alloc] initWithFormat:@"%d", moduleCount];

    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Module selected" message:message delegate:nil cancelButtonTitle:@"Ok" otherButtonTitles:nil];

    [alert show];

    if (component == kPartComponent) {
        return [self.parts count];
    }
    else if (component == kSubjectComponent) {
        return [self.courses count];
    }
    else return moduleCount; // problem is likely to be here where i return the count, the picker is only showing 3 modules for each section not the full amount





}

#pragma mark Picker Delegate Methods
-(NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component {



    Parts *p = [self.parts objectAtIndex:row];

    Course *c = [self.courses objectAtIndex:row];

    Modules *m = [self.modules objectAtIndex:row];


    if (component == kPartComponent) {
        return p.part;
    }

    else if (component == kModuleComponent) {
        return m.name;
    }

    else return c.course;


}

- (CGFloat)pickerView:(UIPickerView *)pickerView widthForComponent:(NSInteger)component
{
    if(component == 0)
        return 40.0;
    else if(component == 1)
        return 85.0;
    else
        return 125.0;

}

-(void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component {


     if (component == kSubjectComponent) {

     Course *selectedCourse;
     selectedCourse = [self.courses objectAtIndex:row];
     NSString *courseComp = [selectedCourse valueForKey:@"course"];

     AppDelegate *delegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];

     NSManagedObjectContext *context = [delegate managedObjectContext];

     NSEntityDescription *entityModules = [NSEntityDescription entityForName:@"Modules" inManagedObjectContext:context];

     NSFetchRequest *fetchRequestModules = [[NSFetchRequest alloc] init];
     [fetchRequestModules setEntity:entityModules];

     NSPredicate * modSubCondition = [NSPredicate predicateWithFormat:@"(courses.course == %@)", courseComp];
     NSPredicate * modPartCondition = [NSPredicate predicateWithFormat:@"(parts.part == %@)", globalPart];
     NSPredicate * compoundPredicate = [NSCompoundPredicate andPredicateWithSubpredicates:[NSArray arrayWithObjects:modSubCondition, modPartCondition, nil]];

     [fetchRequestModules setPredicate:compoundPredicate];

     NSSortDescriptor *sortDescriptorModules = [[NSSortDescriptor alloc] initWithKey:@"name" ascending:YES]; // This definitely works, proven by changing the ascending bool.
     NSArray *sortDescriptorsModules = [[NSArray alloc] initWithObjects:sortDescriptorModules, nil];

     [fetchRequestModules setSortDescriptors:sortDescriptorsModules];

     NSArray *modulesArray = [context executeFetchRequest:fetchRequestModules error:nil];


         globalSubject = courseComp;

     self.modules = modulesArray;

         moduleCount = [self.modules count];



     [picker selectRow:0 inComponent:kModuleComponent animated:YES];
     [picker reloadComponent:kModuleComponent];
     }

     else if (component == kPartComponent) {

     Parts *selectedParts;
     selectedParts = [self.parts objectAtIndex:row];
     NSString *partsComponent = [selectedParts valueForKey:@"part"];

     AppDelegate *delegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];

     NSManagedObjectContext *context = [delegate managedObjectContext];

     NSEntityDescription *entityModules = [NSEntityDescription entityForName:@"Modules" inManagedObjectContext:context];

     NSFetchRequest *fetchRequestModules = [[NSFetchRequest alloc] init];
     [fetchRequestModules setEntity:entityModules];

     NSPredicate * modSubCondition = [NSPredicate predicateWithFormat:@"(courses.course == %@)", globalSubject];
     NSPredicate * modPartCondition = [NSPredicate predicateWithFormat:@"(parts.part == %@)", partsComponent];
     NSPredicate * compoundPredicate = [NSCompoundPredicate andPredicateWithSubpredicates:[NSArray arrayWithObjects:modSubCondition, modPartCondition, nil]];

     [fetchRequestModules setPredicate:compoundPredicate];

     NSSortDescriptor *sortDescriptorModules = [[NSSortDescriptor alloc] initWithKey:@"name" ascending:YES]; // This definitely works, proven by changing the ascending bool.
     NSArray *sortDescriptorsModules = [[NSArray alloc] initWithObjects:sortDescriptorModules, nil];

     [fetchRequestModules setSortDescriptors:sortDescriptorsModules];

     NSArray *modulesArray = [context executeFetchRequest:fetchRequestModules error:nil];


         globalPart = partsComponent;

     self.modules = modulesArray;

         moduleCount = [self.modules count];



     [picker selectRow:0 inComponent:kModuleComponent animated:YES];
     [picker reloadComponent:kModuleComponent];

     }

}

最佳答案

由于每个组件的内容似乎都依赖于其他组件,因此,当您更改模块或主题时,您似乎应该重新加载整个选择器,否则冒着错误的数组大小来计算计数的风险,这确实会给您您得到的错误。

编辑-仔细查看您的代码!

您的实现-

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

...是错的!

您正在使用同一行变量一次访问所有3个数组,而不检查需要哪个数组,因此如果组件的行为16,它也将尝试为模块数组获取objectAtIndex:16。您需要以与其他方法相同的方式检查要访问的数组。

关于iphone - 选择器将仅显示3个对象,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/10137552/

10-12 04:00
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