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1. setNeedDisplay和layoutifNeeded什么关系？

UIView的setNeedsDisplay和setNeedsLayout两个方法都是异步执行的，而setNeedsDisplay会自动调用drawRect方法，这样可以拿到UICraphicsGetCurrent进行绘制，而setNeedsDisplay会默认调用layoutSubviews，给当前的视图做标记，layoutifNeeded查找是否标记，如果有标记会立即刷新。只有setNeedslayout和layoutIfNeeded二者结合起来使用，才能立即刷新。

2. btn扩大相应范围

  1. 自定义View自己实现hitTest:(CGPoint)point withEvent:(UIEvent *)event方法，再函数体内部实现判断是否拦截手势。
#import "TestView.h"

@implementation TestView

- (instancetype)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        [self loadUI];
    }
    return self;
}

- (void)loadUI {
    self.button = [UIButton buttonWithType:UIButtonTypeCustom];
    self.button.frame = CGRectMake(50, 50, 100, 100);
    self.button.backgroundColor = UIColor.purpleColor;
    [self.button addTarget:self action:@selector(buttonClick) forControlEvents:UIControlEventTouchUpInside];
    [self addSubview:self.button];
}

// 此处拦截事件传递
- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event {
    if (CGRectContainsPoint(self.bounds, point)) {
        return self.button;
    }
    return [super hitTest:point withEvent:event];
}

- (void)buttonClick {
    NSLog(@"点击");
}
  1. 继承UIButton,重写-(BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event该方法返回一个布尔值, YES说明点击事件在按钮frame中,NO说明点击事件不在按钮的frame中,因此将按钮frame周围等距离的区域内的点击事件都返回YES,便达到了扩大响应范围的目的。
TestButton.h文件
#import <UIKit/UIKit.h>

NS_ASSUME_NONNULL_BEGIN
@interface TestButton : UIButton
@property (nonatomic, assign) CGSize touchSize;
@end
NS_ASSUME_NONNULL_END

TestButton.m文件
#import "TestButton.h"

@implementation TestButton

- (BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event {
    
    CGRect bounds = self.bounds;
    CGFloat widthDelta = MAX(self.touchSize.width - bounds.size.width, 0);
    CGFloat heightDelta = MAX(self.touchSize.height - bounds.size.height, 0);
    CGRect NewBounds = CGRectInset(bounds, - 0.5 * widthDelta, - 0.5 * heightDelta);
    return CGRectContainsPoint(NewBounds, point);
}

@end


调用
self.button = [TestButton buttonWithType:UIButtonTypeCustom];
self.button.frame = CGRectMake(50, 100, 200, 50);
self.button.backgroundColor = UIColor.orangeColor;
[self.button addTarget:self action:@selector(click) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:self.button];
self.button.touchSize = CGSizeMake(300, 100);