iOS：处理长按并拖动以选择另一个按钮。 （如键盘）

我很难找到有关如何处理触摸事件以支持与键盘类似的行为的正确文档。

我想要的是一个按钮，当我长按它时，它会在按钮上方显示一个自定义视图控制器，但我希望用户能够将手指拖动到其他按钮之一（无需将手指离开屏幕） 。

我长按按钮，它是自定义视图控制器的所有设置和工作。我不知道如何支持从视图控制器中的第一个按钮拖动到另一个按钮以便能够选择它。

我尝试使用子类 UIButton 尝试这样做：

[self addTarget:self action:@selector(onDragOver:) forControlEvents:UIControlEventTouchDragEnter];

但这是行不通的。

我也发现了这个问题长按后如何跟踪按钮选择？ https://stackoverflow.com/questions/20740411/how-to-track-button-selection-after-long-press这正是我想要复制的功能。但没有答案。

这是我的解决方案。诀窍是你必须使用 hitTest: 。

首先，向普通按钮添加手势识别器 - 您想要打开上下文菜单/自定义视图控制器的按钮。

然后在手势识别器回调中，使用 hitTest: 来确定用户是否位于您的自定义按钮上并手动更新其状态。

- (id) init {
    //add a long press gesture recognizer
    UILongPressureGestureRecognizer * gesture = [[UILongPressureGestureRecognizer alloc] initWithTarget:self action:@selector(onLongTap:)];
    [self.myButton addGestureRecognizer:gesture];
}

- (void) onLongTap:(UIGestureRecognizer *) gesture {

    if(gesture.state == UIGestureRecognizerStateBegan) {
        //display your view controller / context menu over the button
    }

    if(gesture.state == UIGestureRecognizerStateEnded) {
        //gesture stopped, use hitTest to find if their finger was over a context button

        CGPoint location = [gesture locationInView:self.view];
        CGPoint superviewLocation = [self.view.superview convertPoint:location fromView:self.view];
        UIView * view = [self.view.superview hitTest:superviewLocation withEvent:nil];

        if([view isKindOfClass:[MMContextMenuButton class]]) {
            //their finger was over my custom button, tell the button to send actions
            MMContextMenuButton * button = (MMContextMenuButton *) view;
            [self hideAndSendControlEvents:UIControlEventTouchUpInside];
            if(self.draggedContextMenuButton == button) {
                self.draggedContextMenuButton = nil;
            }
        }

        if(self.draggedContextMenuButton) {
            [self sendActionsForControlEvents:UIControlEventTouchUpInside];
        }

        self.draggedContextMenuButton = nil;
    }

    if(gesture.state == UIGestureRecognizerStateChanged) {
        //gesture changed, use hitTest to see if their finger
        //is over a button. Manually have to tell the button
        //that it should update it's state.

        CGPoint location = [gesture locationInView:self.view];
        CGPoint superviewLocation = [self.view.superview convertPoint:location fromView:self.view];
        UIView * view = [self.view.superview hitTest:superviewLocation withEvent:nil];

        if([view isKindOfClass[MMContextMenuButton class]]) {
            MMContextMenuButton * button = (MMContextMenuButton *) view;
            if(self.draggedContextMenuButton != button) {
                [self.draggedContextMenuButton dragOut];
            }
            self.draggedContextMenuButton = button;
            [button dragOver];
        }
    }
}


//////////////


#import "MMContextMenuButton.h"
#import "MMContextMenus.h"

@implementation MMContextMenuButton

- (id) initWithCoder:(NSCoder *)aDecoder {
    self = [super initWithCoder:aDecoder];
    self.layer.cornerRadius = 4;
    self.adjustsImageWhenHighlighted = FALSE;
    self.adjustsImageWhenDisabled = FALSE;
    self.backgroundColor = [UIColor clearColor];
    [self setTitleColor:[UIColor whiteColor] forState:UIControlStateHighlighted];
    [self setTitleColor:[UIColor colorWithRed:0.435  green:0.745  blue:0.867 alpha:1] forState:UIControlStateNormal];
    [self addTarget:self action:@selector(onHighlight:) forControlEvents:UIControlEventTouchDown];
    [self addTarget:self action:@selector(onRelease:) forControlEvents:UIControlEventTouchUpOutside&UIControlEventTouchUpOutside];
    return self;
}

- (void) onHighlight:(id) sender {
    self.backgroundColor = [UIColor colorWithRed:0.435  green:0.745  blue:0.867 alpha:1];
}

- (void) onRelease:(id) sender {
    self.backgroundColor = [UIColor clearColor];
}

- (void) hideAndSendControlEvents:(UIControlEvents) events {
    [self dragOut];
    [self sendActionsForControlEvents:events];
    [[MMContextMenus instance] hideContextMenus];
}

- (void) dragOver {
    self.highlighted = TRUE;
    self.backgroundColor = [UIColor colorWithRed:0.435  green:0.745  blue:0.867 alpha:1];
}

- (void) dragOut {
    self.highlighted = FALSE;
    self.backgroundColor = [UIColor clearColor];
}

@end