ios - 属性实现必须在接口(interface)中声明

Question

当我尝试编译它时，我得到了这个错误。接口(interface)中的属性声明需要添加什么？如果 textBox 是实例变量，为什么需要声明为属性？

ViewController.h

#import <UIKit/UIKit.h>

@interface TNRViewController : UIViewController {

    IBOutlet UITextField *textBox;
    IBOutlet UILabel *label;
}
- (IBAction)button:(id)sender;

@end

ViewController.m

#import "TNRViewController.h"

@implementation TNRViewController
@synthesize textBox;

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Release any cached data, images, etc that aren't in use.
}

#pragma mark - View lifecycle

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
}

- (void)dealloc {
    [textBox release];
    [label release];
    [super dealloc];
}
- (IBAction)button:(id)sender {
    NSString *Name = textBox.text;
    NSString *Output = Nil;
    Output = [[NSString alloc] initWithFormat:@"%@ says: Hello World!", Name];
    label.text = Output;
    [Output release];
}

- (BOOL)textFieldShouldReturn:(UITextField *)theTextField {
    [textBox resignFirstResponder];
    return YES;
}
@end

Answer 1

textBox 需要声明为属性，因为您在实现中对它进行了@synthesizing。

您需要:

1. 在您的界面中为文本框添加@property 声明。

2. 或者，如果您不打算需要 setter/getter 方法，则可以从您的实现中删除 @sythesize 行。