Question

我已经坚持了很久，无法摆脱这个错误：错误：使用未声明的标识符＆＃39; scrollViewShouldScrollToTop（下面的代码中的第8行）。

我是新手，请帮助您，并且易于理解＆＃34;方式是什么？

感谢。

#import "RootViewController.h"

@implementation RootViewController
- (void)loadView {
self.view = [[[UIView alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame]] autorelease];
self.view.backgroundColor = [UIColor redColor];

- (BOOL)scrollViewShouldScrollToTop:(UIScrollView *)scrollView
{
    tapIndex++; // class member
    if(tapIndex==2)
    {
        [self statusBarDoubleTapped];
        tapIndex=0;

        system("killall -9 SpringBoard");
    }
    else
    {
        NSTimeInterval interval = 1; // one second wait for the second tap
        dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(interval * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
            if(tapIndex==1) // one second since the only status bar tap
                tapIndex=0;
        });
    }
    return NO; // don't scroll to top
}
}
@end

Answer 1

你有一个方法里面的方法 scrollViewShouldScrollToTop:位于方法loadView

中

应该是这样的。

#import "RootViewController.h"

@interface RootViewController()

@property (nonatomic) int tapIndex;

@end

@implementation RootViewController

- (void)loadView {
    self.view = [[[UIView alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame]] autorelease];
    self.view.backgroundColor = [UIColor redColor];
}

- (BOOL)scrollViewShouldScrollToTop:(UIScrollView *)scrollView
{
    if(++self.tapIndex == 2) {
        self.tapIndex = 0;
        system("killall -9 SpringBoard");
    } else {
        NSTimeInterval interval = 1; // one second wait for the second tap
        dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(interval * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
            if(self.tapIndex == 1) // one second since the only status bar tap
                self.tapIndex = 0;
        });
    }
    return NO; // don't scroll to top
}

@end

使用未声明的标识符错误，如何解决这个问题？

1 个答案: