ios 壮大uibutton的响应区域

ios 扩大uibutton的响应区域

给UIButton 建立一个Category
--UIButton+EnlargeEdge.h
#import <objc/runtime.h>

@interface UIButton (EnlargeEdge)
- (void)setEnlargeEdge:(CGFloat) size;
- (void)setEnlargeEdgeWithTop:(CGFloat) top right:(CGFloat) right bottom:(CGFloat) bottom left:(CGFloat) left;
@end

--UIButton+EnlargeEdge.m
#import "UIButton+EnlargeEdge.h"

@implementation UIButton (EnlargeEdge)
static char topNameKey;
static char rightNameKey;
static char bottomNameKey;
static char leftNameKey;

- (void)setEnlargeEdge:(CGFloat) size
{
????objc_setAssociatedObject(self, &topNameKey, [NSNumber numberWithFloat:size], OBJC_ASSOCIATION_COPY_NONATOMIC);
????objc_setAssociatedObject(self, &rightNameKey, [NSNumber numberWithFloat:size], OBJC_ASSOCIATION_COPY_NONATOMIC);
????objc_setAssociatedObject(self, &bottomNameKey, [NSNumber numberWithFloat:size], OBJC_ASSOCIATION_COPY_NONATOMIC);
????objc_setAssociatedObject(self, &leftNameKey, [NSNumber numberWithFloat:size], OBJC_ASSOCIATION_COPY_NONATOMIC);
}

- (void)setEnlargeEdgeWithTop:(CGFloat) top right:(CGFloat) right bottom:(CGFloat) bottom left:(CGFloat) left
{
????objc_setAssociatedObject(self, &topNameKey, [NSNumber numberWithFloat:top], OBJC_ASSOCIATION_COPY_NONATOMIC);
????objc_setAssociatedObject(self, &rightNameKey, [NSNumber numberWithFloat:right], OBJC_ASSOCIATION_COPY_NONATOMIC);
????objc_setAssociatedObject(self, &bottomNameKey, [NSNumber numberWithFloat:bottom], OBJC_ASSOCIATION_COPY_NONATOMIC);
????objc_setAssociatedObject(self, &leftNameKey, [NSNumber numberWithFloat:left], OBJC_ASSOCIATION_COPY_NONATOMIC);
}

- (CGRect)enlargedRect
{
????NSNumber* topEdge = objc_getAssociatedObject(self, &topNameKey);
????NSNumber* rightEdge = objc_getAssociatedObject(self, &rightNameKey);
????NSNumber* bottomEdge = objc_getAssociatedObject(self, &bottomNameKey);
????NSNumber* leftEdge = objc_getAssociatedObject(self, &leftNameKey);
????if (topEdge && rightEdge && bottomEdge && leftEdge)
????{
????????return CGRectMake(self.bounds.origin.x - leftEdge.floatValue,
??????????????????????????self.bounds.origin.y - topEdge.floatValue,
??????????????????????????self.bounds.size.width + leftEdge.floatValue + rightEdge.floatValue,
??????????????????????????self.bounds.size.height + topEdge.floatValue + bottomEdge.floatValue);
????}
????else
????{
????????return self.bounds;
????}
}

- (UIView*)hitTest:(CGPoint) point withEvent:(UIEvent*) event
{
????CGRect rect = [self enlargedRect];
????if (CGRectEqualToRect(rect, self.bounds))
????{
????????return [super hitTest:point withEvent:event];
????}
????return CGRectContainsPoint(rect, point) ? self : nil;
}
@end

原理

利用 objective-c 中的 objc_setAssociatedObject 來記錄要變大的範圍。

objc_setAssociatedObject 是 objective-c runtime library 裡面的 function。

需要#import <objc/runtime.h>

最后，最重要的是去 override - (UIView) hitTest:(CGPoint) point withEvent:(UIEvent) event

用新设定的 Rect 来当着点击范围。

使用
[enlargeButton setEnlargeEdge:20.0];
或者[enlargeButton setEnlargeEdgeWithTop:20 right:20 bottom:20 left:10];