objective-c - 摇动手势和 firstResponder

Question

我正在尝试让摇动手势起作用。这是一些代码

在我的实现文件中

- (void)motionBegan:(UIEventSubtype)motion withEvent:(UIEvent *)event
{
    if(event.type == UIEventSubtypeMotionShake)
    {

        NSLog(@"Shake gesture detected");

    }
}

- (BOOL)canBecomeFirstResponder
{ 
    return YES; 
}

我读到，为了使摇动手势起作用，UIView 应该是 firstResponder。这就是我在实现中添加该代码的原因

if(self.view.isFirstResponder)
    {
        NSLog(@"first");
    }
    else
    {
        NSLog(@"no");
    }

- (void)viewDidAppear {
    [self becomeFirstResponder];
}

当我运行应用程序时，NSLog 的输出为 NO。我想念什么？以及如何让摇动手势起作用

Answer 1

我猜您是在 UIViewController 中执行此操作？那是不正确的......你必须像这样子类化 UIView:

ShakeView.h:

//
//  ShakeView.h
//

#import <UIKit/UIKit.h>

@interface ShakeView : UIView {

}

- (void)motionEnded:(UIEventSubtype)motion withEvent:(UIEvent *)event;
- (BOOL)canBecomeFirstResponder;

@end

ShakeView.m:

//
//  ShakeView.m
//

#import "ShakeView.h"

@implementation ShakeView

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
    }
    return self;
}

- (void)motionEnded:(UIEventSubtype)motion withEvent:(UIEvent *)event
{
    if ( event.subtype == UIEventSubtypeMotionShake ) {
    }    
    if ( [super respondsToSelector:@selector(motionEnded:withEvent:)] ) {
        [super motionEnded:motion withEvent:event];
    }
}

- (BOOL)canBecomeFirstResponder
{
    return YES;
}

@end

然后使用 ShakeView 而不是您的“普通”UIView 并在您的 UIViewController 中实现它:

- (void)motionEnded:(UIEventSubtype)motion withEvent:(UIEvent *)event
{
    NSLog(@"Shake happend …");
}

- (void)viewDidAppear:(BOOL)animated
{
    [self.view becomeFirstResponder];
    [super viewDidAppear:animated];
}

- (void)viewWillDisappear:(BOOL)animated
{
    [self.view resignFirstResponder];
    [super viewWillDisappear:animated];
}

就是这样。希望对您有所帮助:)