ios 扩大uibutton的响应区域

转载自: http://wenrisheng.iteye.com/blog/1987996
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;

}

}

- (BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event

{

CGRect rect = [self enlargedRect];

if (CGRectEqualToRect(rect, self.bounds))

{

return [super pointInside:point withEvent:event];

}

return CGRectContainsPoint(rect, point) ? YES : NO;

}

/*

- (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];