如何使用Eigen :: Matrix作为参考(How to use Eigen::Matrix by reference)

 例如，我添加这个 
 
 步骤1 
 
 创建One UIPicker ， UItextField和NSArray以加载详细信息 
 
@interface ViewController ()<UITextFieldDelegate,UIPickerViewDataSource,UIPickerViewDelegate>
{

UITextField *myTextField;
UIPickerView *myPickerView;
NSArray *pickerArray;
}

@end
 
 第2步 
 
 在您的ViewDidLoad调用选择器方法 
 
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
[self addPickerView];
}
 
 步骤3 
 
create the picker, textfield and done button

-(void)addPickerView{
pickerArray = [[NSArray alloc]initWithObjects:@"Chess",
               @"Cricket",@"Football",@"Tennis",@"Volleyball", nil];
myTextField = [[UITextField alloc]initWithFrame:
               CGRectMake(10, 100, 300, 30)];
myTextField.borderStyle = UITextBorderStyleRoundedRect;
myTextField.textAlignment = NSTextAlignmentCenter;
myTextField.delegate = self;
[self.view addSubview:myTextField];
[myTextField setPlaceholder:@"Pick a Sport"];
myPickerView = [[UIPickerView alloc]init];
myPickerView.dataSource = self;
myPickerView.delegate = self;
myPickerView.showsSelectionIndicator = YES;
UIBarButtonItem *doneButton = [[UIBarButtonItem alloc]
                               initWithTitle:@"Done" style:UIBarButtonItemStyleDone
                               target:self action:@selector(done:)];
UIToolbar *toolBar = [[UIToolbar alloc]initWithFrame:
                      CGRectMake(0, self.view.frame.size.height-
                                 myPickerView.frame.size.height-50, 320, 50)];
[toolBar setBarStyle:UIBarStyleBlackOpaque];
NSArray *toolbarItems = [NSArray arrayWithObjects:
                         doneButton, nil];
[toolBar setItems:toolbarItems];
myTextField.inputView = myPickerView;
myTextField.inputAccessoryView = toolBar;

}
 
 步骤4 
 
 如果用户按下完成按钮，则退出选择器 
 
-(void)done:(id)sender
{

[myTextField resignFirstResponder];
}
 
 步骤-5 
 
 PickerView委托方法 
 
#pragma mark - Picker View Data source
-(NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView{
return 1;
}
-(NSInteger)pickerView:(UIPickerView *)pickerView
numberOfRowsInComponent:(NSInteger)component{
return [pickerArray count];
}

#pragma mark- Picker View Delegate

-(void)pickerView:(UIPickerView *)pickerView didSelectRow:
(NSInteger)row inComponent:(NSInteger)component{
[myTextField setText:[pickerArray objectAtIndex:row]];
}
- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:
(NSInteger)row forComponent:(NSInteger)component{
return [pickerArray objectAtIndex:row];
}
 
 这里我附上了示例项目 
 
 样本输出就像 
 
  
 
 更新 
 
 如果您使用隐藏的按钮，则pickerview使用此选项 
 
-(void)donePressed:(id)sender
{
  [self.myPickerView removeFromSuperview];

}
 
 按下按钮时调用此方法 
 
[self funtion];

for example I add this 
 
Step-1
 
Create the One UIPicker,UItextField and NSArray for load the details
 
@interface ViewController ()<UITextFieldDelegate,UIPickerViewDataSource,UIPickerViewDelegate>
{

UITextField *myTextField;
UIPickerView *myPickerView;
NSArray *pickerArray;
}

@end
 
Step-2
 
on your ViewDidLoad call the picker method like
 
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
[self addPickerView];
}
 
Step-3
 
create the picker, textfield and done button

-(void)addPickerView{
pickerArray = [[NSArray alloc]initWithObjects:@"Chess",
               @"Cricket",@"Football",@"Tennis",@"Volleyball", nil];
myTextField = [[UITextField alloc]initWithFrame:
               CGRectMake(10, 100, 300, 30)];
myTextField.borderStyle = UITextBorderStyleRoundedRect;
myTextField.textAlignment = NSTextAlignmentCenter;
myTextField.delegate = self;
[self.view addSubview:myTextField];
[myTextField setPlaceholder:@"Pick a Sport"];
myPickerView = [[UIPickerView alloc]init];
myPickerView.dataSource = self;
myPickerView.delegate = self;
myPickerView.showsSelectionIndicator = YES;
UIBarButtonItem *doneButton = [[UIBarButtonItem alloc]
                               initWithTitle:@"Done" style:UIBarButtonItemStyleDone
                               target:self action:@selector(done:)];
UIToolbar *toolBar = [[UIToolbar alloc]initWithFrame:
                      CGRectMake(0, self.view.frame.size.height-
                                 myPickerView.frame.size.height-50, 320, 50)];
[toolBar setBarStyle:UIBarStyleBlackOpaque];
NSArray *toolbarItems = [NSArray arrayWithObjects:
                         doneButton, nil];
[toolBar setItems:toolbarItems];
myTextField.inputView = myPickerView;
myTextField.inputAccessoryView = toolBar;

}
 
Step-4
 
if user press the Done Button resign the picker
 
-(void)done:(id)sender
{

[myTextField resignFirstResponder];
}
 
Step-5
 
PickerView Delegate methods
 
#pragma mark - Picker View Data source
-(NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView{
return 1;
}
-(NSInteger)pickerView:(UIPickerView *)pickerView
numberOfRowsInComponent:(NSInteger)component{
return [pickerArray count];
}

#pragma mark- Picker View Delegate

-(void)pickerView:(UIPickerView *)pickerView didSelectRow:
(NSInteger)row inComponent:(NSInteger)component{
[myTextField setText:[pickerArray objectAtIndex:row]];
}
- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:
(NSInteger)row forComponent:(NSInteger)component{
return [pickerArray objectAtIndex:row];
}
 
here I attached the sample project 
 
Sample Output like
 
 
Update
 
if you are used the button hidden the pickerview use this 
 
-(void)donePressed:(id)sender
{
  [self.myPickerView removeFromSuperview];

}
 
when you pressed the button call this method
 
[self funtion];