button扩大响应区

方法一：

#import

@interface UIButton (EnlargeTouchArea)

- (void)setEnlargeEdgeWithTop:(CGFloat) top right:(CGFloat) right bottom:(CGFloat) bottom left:(CGFloat) left;

@end

#import "UIButton+EnlargeTouchArea.h"

#import

@implementation UIButton (EnlargeTouchArea)

static char topNameKey;

static char rightNameKey;

static char bottomNameKey;

static char leftNameKey;

- (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;

}

方法二：

Apple的iOS人机交互设计指南中指出，按钮点击热区应不小于44x44pt，否则这个按钮就会让用户觉得“很难用”，因为明明点击上去了，却没有任何响应。

但我们有时做自定义Button的时候，设计图上的给出按钮尺寸明显要小于这个数。例如我之前做过的自定义Slider上的Thumb只有12x12pt，做出来后我发现自己根本点不到按钮……

这个问题在WWDC 2012 Session 216视频中提到了一种解决方式。它重写了按钮中的pointInside方法，使得按钮热区不够44×44大小的先自动缩放到44×44，再判断触摸点是否在新的热区内。

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

{

CGRect bounds = self.bounds;

//若原热区小于44x44，则放大热区，否则保持原大小不变

CGFloat widthDelta = MAX(44.0 - bounds.size.width, 0);

CGFloat heightDelta = MAX(44.0 - bounds.size.height, 0);

bounds = CGRectInset(bounds, -0.5 * widthDelta, -0.5 * heightDelta);

return CGRectContainsPoint(bounds, point);

}