UIButton小技巧----點擊事件的範圍

UIButton小技巧—-點擊事件的範圍

起因

      在開發過程中對於UIbutton的點擊事件，有時按鈕太小不能被輕易點擊到，希望放大點擊的範圍。

解決方案

     通過添加Category，重寫pointInside: withEvent:方法，通過判斷點擊的位置是否在希望響應事件所在範圍，在期望的範圍內就響應事件，不再就不響應。

代碼

#import <UIKit/UIKit.h>

@interface UIButton (TouchScope)

- (void)expandTouchScope:(UIEdgeInsets)edgeInsets;

@end

#import "UIButton+TouchScope.h"
#import <objc/runtime.h>

static NSString *expandRectXKey = @"expandRectX";
static NSString *expandRectYKey = @"expandRectY";
static NSString *expandRectWidthKey = @"expandRectWidthKey";
static NSString *expandRectHeightKey = @"expandRectHeightKey";

@implementation UIButton (TouchScope)

- (void)expandTouchScope:(UIEdgeInsets)edgeInsets {
    objc_setAssociatedObject(self,
                             &expandRectYKey,
                             [NSNumber numberWithFloat:self.bounds.origin.y - edgeInsets.top],
                             OBJC_ASSOCIATION_COPY_NONATOMIC);
    objc_setAssociatedObject(self,
                             &expandRectXKey,
                             [NSNumber numberWithFloat:self.bounds.origin.x - edgeInsets.left],
                             OBJC_ASSOCIATION_COPY_NONATOMIC);
    objc_setAssociatedObject(self,
                             &expandRectWidthKey,
                             [NSNumber numberWithFloat:self.frame.size.width + edgeInsets.left + edgeInsets.right],
                             OBJC_ASSOCIATION_COPY_NONATOMIC);
    objc_setAssociatedObject(self,
                             &expandRectHeightKey,
                             [NSNumber numberWithFloat:self.frame.size.height + edgeInsets.top + edgeInsets.bottom],
                             OBJC_ASSOCIATION_COPY_NONATOMIC);
}

- (CGRect)expandRect {
    NSNumber *expandRectX = objc_getAssociatedObject(self, &expandRectXKey);
    NSNumber *expandRectY = objc_getAssociatedObject(self, &expandRectYKey);
    NSNumber *expandRectWidth = objc_getAssociatedObject(self, &expandRectWidthKey);
    NSNumber *expandRectHeight = objc_getAssociatedObject(self, &expandRectHeightKey);
    return CGRectMake(expandRectX.floatValue,
                      expandRectY.floatValue,
                      expandRectWidth.floatValue,
                      expandRectHeight.floatValue);
}

// 響應用戶的點擊事件
- (BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event {
    CGRect buttonRect = [self expandRect];
    if (CGRectEqualToRect(buttonRect, self.bounds)) {
        return [super pointInside:point withEvent:event];
    }
    return CGRectContainsPoint(buttonRect, point) ? YES : NO;
}

@end

應用

 [button expandTouchScope:UIEdgeInsetsMake(20, 20, 20, 20)];

紅色區域爲Button，藍色區域是向外拓展的20的點擊範圍。設置完成在藍色、紅色範圍內都可以響應事件。