在 UIActionSheet 中添加 UIPickerView 时，iOS 7 上出现无效的上下文错误？

Question

我在 UIActionSheet 中有一个 UIPickerView，并以 SO 中许多其他人建议的方式完成了该操作：

Add UIPickerView & a Button in Action sheet - How?

how to add UIPickerView in UIActionSheet

到目前为止，在 iOS 7 上测试我的应用时，这些解决方案一直运行良好。它仍然有效，但我在 Xcode 运行时收到很多“无效上下文 0x0”警告。

错误也带有一个很好的消息：

CGContextSetFillColorWithColor：无效的上下文 0x0。这是一个严重的错误。此应用程序或它使用的库正在使用无效的上下文，从而导致系统稳定性和可靠性的整体下降。此通知是出于礼貌：请解决此问题。这将成为即将到来的更新中的致命错误。

可能是 Apple 最终想要停止这种解决方案，还是我们可以解决或修复它？

Answer 1

-(void)viewDidLoad
{
  [super viewDidLoad];
// Make Your own Action sheet

myCustomeActionSheet=[[UIView alloc] initWithFrame:CGRectMake(0,self.view.frame.size.height+1,self.view.frame.size.width,215)];
myCustomeActionSheet.backgroundColor=[UIColor whiteColor];
[self.view addSubview:myCustomeActionSheet];
}

// 使用此代码打开日期选择器或 UiPicker 视图

-(void)OpenActionSheet:(Boolean)isDatePickere
{
SelectedString=Nil;
if (datepickerView) {
    [datepickerView removeFromSuperview];
    datepickerView=Nil;
}
if (picker) {
    [picker removeFromSuperview];
    picker=Nil;
}
if (isDatePickere)
{
    // Add the  Datepicker
    datepickerView= [[UIDatePicker alloc] init];
    datepickerView.datePickerMode = UIDatePickerModeDateAndTime;
    datepickerView.minimumDate=[NSDate date];
    [myCustomeActionSheet addSubview:datepickerView];
}
else
{
    // Add Picker View
    picker = [[UIPickerView alloc] initWithFrame:CGRectMake(0,40, 320, 216)];
    picker.showsSelectionIndicator=YES;
    picker.dataSource = self;
    picker.delegate = self;
    [myCustomeActionSheet addSubview:picker];
}

UIToolbar *tools=[[UIToolbar alloc]initWithFrame:CGRectMake(0, 0,320,40)];
tools.barStyle=UIBarStyleBlackOpaque;
[myCustomeActionSheet addSubview:tools];

UIBarButtonItem *doneButton=[[UIBarButtonItem alloc]initWithTitle:@"Done" style:UIBarButtonItemStyleBordered target:self action:@selector(btnActinDoneClicked)];
doneButton.imageInsets=UIEdgeInsetsMake(200, 6, 50, 25);
UIBarButtonItem *CancelButton=[[UIBarButtonItem alloc]initWithTitle:@"Cancel" style:UIBarButtonItemStyleBordered target:self action:@selector(btnActinCancelClicked)];

UIBarButtonItem *flexSpace= [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace target:nil action:nil];

NSArray *array = [[NSArray alloc]initWithObjects:CancelButton,flexSpace,flexSpace,doneButton,nil];

[tools setItems:array];

//picker title
UILabel *lblPickerTitle=[[UILabel alloc]initWithFrame:CGRectMake(60,8, 200, 25)];
lblPickerTitle.text=@"Select";
lblPickerTitle.backgroundColor=[UIColor clearColor];
lblPickerTitle.textColor=[UIColor whiteColor];
lblPickerTitle.textAlignment=NSTextAlignmentCenter;
lblPickerTitle.font=[UIFont boldSystemFontOfSize:15];
[tools addSubview:lblPickerTitle];

[UIView animateWithDuration:0.5 animations:^{
    myCustomeActionSheet.frame=CGRectMake(0,self.view.frame.size.height-myCustomeActionSheet.frame.size.height,myCustomeActionSheet.frame.size.width,myCustomeActionSheet.frame.size.height);
} completion:^(BOOL finished)
 {
     
 }];
}

pragma -mark 条形按钮操作

-(void)btnActinDoneClicked
{
if (SelectedString==Nil)
{
    SelectedString=[pickerArrayList objectAtIndex:0];
}

if (datepickerView)
{
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    
    NSLocale *posix = [[NSLocale alloc] initWithLocaleIdentifier:@"en_US_POSIX"];
    [dateFormatter setLocale:posix];
    [dateFormatter setTimeZone:[NSTimeZone systemTimeZone]];
    [dateFormatter setDateFormat:@"DD/MM/yy hh:mm a"];
    
    [selectedButton setTitle:[dateFormatter stringFromDate:datepickerView.date] forState:UIControlStateNormal];
}
else
    [selectedButton setTitle:SelectedString forState:UIControlStateNormal];

    [self performSelector:@selector(btnActinCancelClicked) withObject:nil afterDelay:0.10];

 }
-(void)btnActinCancelClicked
{
[UIView animateWithDuration:0.5 animations:^{
    
    viewActiobSheetView.frame=CGRectMake(0,self.view.frame.size.height+1,self.view.frame.size.width,viewActiobSheetView.frame.size.height);
    
}
                 completion:^(BOOL finished)
 {
     [datepickerView removeFromSuperview];
     [picker removeFromSuperview];
     datepickerView=Nil;
     picker=Nil;
 }];
 }

pragma -mark PickerView 委托

 - (UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:  (NSInteger)component reusingView:(UIView *)view
{
  UILabel *label=[[UILabel alloc] initWithFrame:CGRectMake(0, 0, 320, 40)];
  label.text=[pickerArrayList objectAtIndex:row];
  label.textAlignment=NSTextAlignmentCenter;
  label.textColor=[UIColor blackColor];
  return label;
 }
-(NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView;
  {
    return 1;
  }
-(NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component
  {
    return [pickerArrayList count];
  }
 -(void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component
   {
    SelectedString=[pickerArrayList objectAtIndex:row];
   }

Answer 2

此“无效上下文 0x0”警告的解决方法是使用非 nil 标题初始化 UIActionSheet（非 nil 按钮也可以解决错误，但会导致视觉伪影）。

UIActionSheet *actionSheet = [[UIActionSheet alloc] initWithTitle:@"" 
                                                         delegate:nil
                                                cancelButtonTitle:nil
                                           destructiveButtonTitle:nil
                                                otherButtonTitles:nil];

然后，您需要调整操作表的框架，使其在 iOS7 和以前的版本中正确定位（确保在 showInView 方法之后执行此操作）。

CGRect newFrame = actionSheet.frame;
newFrame = self.view.bounds.size.height - myCustomPicker.frame.size.height;
newFrame = myCustomPicker.frame.size.height;
actionSheet.frame = newFrame;

Answer 3

正如上面的 cmets 所指出的，UIActionSheet 不是为子类化或采用其他视图而设计的。

更多信息请点击此处：

https://developer.apple.com/library/ios/documentation/uikit/reference/UIActionSheet_Class/Reference/Reference.html#//apple_ref/doc/uid/TP40006801-CH3-DontLinkElementID_2

一种方法是仔细查看 DateCell 示例代码并将其更改为使用 UIPickerView：

https://developer.apple.com/library/ios/samplecode/DateCell/Introduction/Intro.html#//apple_ref/doc/uid/DTS40008866-Intro-DontLinkElementID_2