如何子类化 UITextView：实现水平滑动

Question

我正在尝试在 UITextView 上实现水平滚动。我发现这个解释here。

但是，我不明白如何“子类化”a UITextView。给出的代码以及我尝试实现的代码如下：

@interface SwipeableTextView : UITextView {
}

@end

@implementation SwipeableTextView

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

    [self.superview touchesBegan:touches withEvent:event];

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

    [self.superview touchesMoved:touches withEvent:event];
}

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

    [self.superview touchesEnded:touches withEvent:event];
} 

@end

显然，这应该覆盖普通的 UITextView，然后我可以通过引用 SwipeableTextView 来调用它（例如SwipeableTextView.text = @"Some Text";)。我的问题是，我应该把这段代码放在哪里？在我的 .m 或 .h 文件中？我尝试将其放在 m 文件的实现部分下方，但这不起作用，因为我已经有 @interface 和 @implementation 部分。任何帮助将非常感激。

---

编辑：现在可以使用：

//
//  SwipeTextView.h
//  Swipes
//

#import <Foundation/Foundation.h>

@interface SwipeTextView : UITextView {
    CGPoint     gestureStartPoint;
}

@property CGPoint gestureStartPoint;


@end

M 文件

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

#import "SwipeTextView.h"
#define kMinimumGestureLength    10
#define kMaximumVariance         5

@implementation SwipeTextView
@synthesize gestureStartPoint;

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

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

    [self.superview touchesBegan:touches withEvent:event];

}

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

    [super touchesMoved:touches withEvent:event];
    [self.superview touchesMoved:touches withEvent:event];

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

    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

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

    }

}

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

    [self.superview touchesEnded:touches withEvent:event];
} 




@end

最后，这就是我在 ViewController 中创建此自定义 UITextView 的子类的方法：

// UITextView
CGRect aFrame = CGRectMake(0, 100, 320, 200);
aSwipeTextView = [[SwipeTextView alloc] initWithFrame:aFrame];
aSwipeTextView.text = @"Some sample text. Some sample text. Some sample text.";
[self.view addSubview:aSwipeTextView];

Answer 1

好吧，这就是你要做的。

当您想要子类化一个对象时，您可以为其创建 .h 和 .m 文件。

创建一个名为 SwipeableTextView.h 的文件并在其中插入以下代码：

#import <Foundation/Foundation.h>

    @interface SwipeableTextView : UITextView {

    }

@end

然后创建一个文件 SwipeableTextView.m 并将其插入其中：

#import "SwipeableTextView.h"

@implementation SwipeableTextView

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

    [self.superview touchesBegan:touches withEvent:event];

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

    [self.superview touchesMoved:touches withEvent:event];
}

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

    [self.superview touchesEnded:touches withEvent:event];
} 

@end

要在项目中使用这个新子类，请执行以下操作。

导入标题：

#import "SwipeableTextView.h"

然后通常创建 UITextView，您可以像这样创建 SwipeableTextView：

SwipeableTextView *sTextView = [[SwipeableTextView alloc] init];

就是这样。
希望有帮助。