定义UITextView的最大方差 [英] Defining maximum variance of an UITextView

问题描述

如果您有普通的 UITextView ，其中包含大量文本，则可以上下滑动：

If you have a normal UITextView with loads of text in it you can swipe up and down:

• 如果以非常水平的方向向左或向右滑动，则不会发生


• 如果以很小的角度向左或向右滑动，则将向上滑动或down

因此，显然存在某种类定义，它告诉 UITextView 何时对滑动做出反应，何时不做出响应。我猜是类似maximumVariance常数。

So there is obviously some kind of class definition which tells the UITextView when to react to a swipe and when not to. Something like a maximumVariance constant, I guess.

我的问题是我试图将 UITextView 子类化为启用向左/向右滑动。但是，您将需要沿相当大的直线滑动，否则，您将向上或向下滑动。所以我的问题是，是否有某种方法可以重新定义UITextView的标准方差变量？

My problem is that I'm trying to subclass an UITextView to enable left/right swipe. However, you will need to swipe in a pretty straight line, otherwise, you'll get an up or down swipe. So my question is if there is someway to re-define the standard variance variable of an UITextView?

这是我的子类.m文件。请注意， kMaximumVariance 并没有任何实际作用，因为标准 UITextView 类提供的任何方差都会覆盖此内容：

Here is my subclass .m file. Note that the kMaximumVariance doesn't really have any effect as this is overwritten by whatever variance the standard UITextView class provides:

//
//  SwipeTextView.m
//  Swipes
//

#import "SwipeTextView.h"
#import "PageView.h"

#define kMinimumGestureLength    15
#define kMaximumVariance         100

@implementation SwipeTextView
@synthesize delegate, gestureStartPoint;


- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
    [super touchesBegan:touches withEvent:event];

    UITouch *touch =[touches anyObject];
    gestureStartPoint = [touch locationInView:self];

}

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {

    [super touchesMoved:touches withEvent:event];


}

-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
    [super touchesEnded:touches withEvent:event];
    [self resignFirstResponder]; // this hides keyboard if horizonal swipe

    UITouch *touch = [touches anyObject];
    CGPoint currentPosition = [touch locationInView:self];

    CGFloat deltaXX = (gestureStartPoint.x - currentPosition.x); // positive = left, negative = right
    CGFloat deltaYY = (gestureStartPoint.y - currentPosition.y); // positive = up, negative = down

    CGFloat deltaX = fabsf(gestureStartPoint.x - currentPosition.x); // will always be positive
    CGFloat deltaY = fabsf(gestureStartPoint.y - currentPosition.y); // will always be positive


    NSLog(@"deltaXX (%.1f) deltaYY (%.1f) deltaX (%.1f) deltaY (%.1f)",deltaXX, deltaYY, deltaX, deltaY);

    if (deltaX >= kMinimumGestureLength && deltaY <= kMaximumVariance) {
        if (deltaXX > 0) {
            NSLog(@"Horizontal Left swipe - FINISHED detected");
        }
        else {
            NSLog(@"Horizontal Right swipe - FINISHED detected");
        }

    }



} 




@end

编辑：

建议取消达到 UITextView 的触摸（见下文）：

Suggestion to cancel touches reaching UITextView (see below):

// Prevent recognizing touches
- (BOOL)gestureRecognizer:(UISwipeGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch {

    if ([gestureRecognizer direction] == UISwipeGestureRecognizerDirectionLeft) {
        // Left swipe: I want to handle this
        return YES;
    }
    if ([gestureRecognizer direction] == UISwipeGestureRecognizerDirectionRight) {
        // Right swipe: I want to handle this
        return YES;
    }
    if ([gestureRecognizer direction] == UISwipeGestureRecognizerDirectionUp) {
        // Up swipe: textView needs to handle this
        return NO;
    }
    if ([gestureRecognizer direction] == UISwipeGestureRecognizerDirectionDown) {
        // Down swipe: textView needs to handle this
        return NO;
    } else
        return YES;
}


-(void)viewDidLoad
{

    UITapGestureRecognizer *GesRec = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(doSomething:)];

    [GesRec setCancelsTouchesInView:NO];
    [self addGestureRecognizer:GesRec];
    [GesRec release];

}


-(void)doSomething
{
    NSLog(@"doSomething");
}

推荐答案

尝试添加 UISwipeGestureRecognizer 到视图并设置 cancelsTouchesInView 设置为false，以免滑动手势通过。

Try adding an UISwipeGestureRecognizer to the view and set cancelsTouchesInView to false so the swipe gesture is not passed through. This should let you detect left and right motion more accurately.

如果这样做不能解决问题，请实现自己的 UIGestureRecognizer子类

If this doesn't do the trick, implement your own subclass of UIGestureRecognizer and add that instead.

编辑

您添加控制器的 viewDidLoad 方法中的 UITextView 的手势识别器。

You add the gesture recognizer to the UITextView in your controller's viewDidLoad method.

在您的委托方法中，您不能在 gestureRecognizer：shouldReceiveTouch中返回 NO 。 ，因为这意味着手势识别器不会检查传入的触摸对象。在您的情况下，您想在水平滑动时返回 YES ，否则返回 NO ，因此，垂直滑动会在水平滑动已由您处理。

In your delegate methods, you can't return NO in gestureRecognizer:shouldReceiveTouch: because it means the gesture recognizer won't examine the incoming touch object. In your case you want to return YES when the swipe is horizontal and NO otherwise, so vertical swipes are passed through while horizontal swipe is completed handled by you.

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