我是编程新手。我对继承有一个基本的怀疑。我在ViewController
有一个UITableView
,当我选择第一行Tableview
时.它将我带到Picker
页面,其中只有我必须从UIPickerView
中选择值,现在很好,我必须在button
的ViewController
中NSLOG
选定的picker
值,这是我面临的小问题。
VIewController.m
- (void)viewDidLoad
{
[super viewDidLoad];
tableview =[[UITableView alloc]initWithFrame:CGRectMake(0,0,([UIScreen mainScreen].bounds.size.width),([UIScreen mainScreen].bounds.size.height/2)) style:UITableViewStyleGrouped];
tableview.delegate=self;
tableview.dataSource=self;
[self.view addSubview:tableview];
button = [UIButton buttonWithType:UIButtonTypeRoundedRect];
[button addTarget:self action:@selector(pressed) forControlEvents:UIControlEventTouchDown];
[button setTitle:@"START " forState:UIControlStateNormal];
button.frame = CGRectMake(62, 250, 196, 37);
[self.view addSubview:button];
thearray= [[NSArray alloc]initWithObjects:@"A",@"B ",@"C",@"D",@"E" ,nil];
[super viewDidUnload];
}
-(void)pressed{
// nslog value..i need here the picker value
}
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
return 1;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{
return 5;
}
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath{
if(indexPath.row==0){
Picker1 *pick= [[Picker1 alloc] init];
[self navigationController] pushViewController:pick animated:YES]
}
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NS IndexPath *)indexPath
{
static NSString *CellIdentifier = @"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleValue1 reuseIdentifier:CellIdentifier];
}
cell.textLabel.text=[thearray objectAtIndex:indexPath.row];
return cell;
}
皮克·
- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView {
return 1;
}
- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component {
return [list count];
}
- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component {
return [list objectAtIndex:row];
}
- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component {
// update label text to show selected option
string=[NSString stringWithFormat:@"%@",[list objectAtIndex:row]];
label.text=string;
[self dismissModalViewControllerAnimated:YES];
}
- (void)viewDidLoad
{
[super viewDidLoad];
list =[[NSMutableArray alloc]init];
[list addObject:@"A"];
[list addObject:@"B"];
[list addObject:@"C"];
}
您可以使用委托
在 picker.m 中,上面的@interface部分执行此操作
@protocol pickerDelegate <NSObject>
-(void)didFinishPicking:(NSString *)pickedStr;
@end
使此协议的属性
@property(nonatomic,weak)id<pickerDelegate>delegate
和 in - (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component method, do this
string=[NSString stringWithFormat:@"%@",[list objectAtIndex:row]];
[self.delegate didFinsihPicking:string];
现在在 viewController .h 中,在方法
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
Picker1 *pick= [[Picker1 alloc] init];
[pick setDelegate : self];
并在 ViewControler.h 中实现 dlegate 方法
-(void)didFinishPicking:(NSString *)pickedStr
{
[self setStr:pickedStr]
}
其中 str 是您需要在 viewController .h 中声明的字符串变量,并在按钮单击事件时打印此字符串
选取器需要一个委托才能将所选值传递回表视图。在 Picker.h 文件的顶部定义委托方法:
@class Picker;
@protocol PickerDelegate <NSObject>
- (void)picker:(Picker *)thePicker didPickValue:(NSString *)theValue;
@end
同样在 Picker.h 文件中,创建与委托的弱连接,该委托将成为表视图控制器:
@property (nonatomic, weak) id <PickerDelegate> delegate;
在表视图控制器中,将委托添加到头文件:
@interface ViewController : UITableViewController <PickerDelegate>
您可以从 Picker.m 调用委托方法,并在 ViewController.m 中实现它:
[self.delegate picker:self didPickValue:[NSString stringWithFormat:@"%@",[list objectAtIndex:row]]];
重要说明:创建选取器时,必须告诉它委托人是谁。您在表视图中执行此操作,因此您调用:
pick.delegate = self;