如何在UIToolbar中添加无间隙的等宽UIButtons？

嘿，我来帮你搞定这个UIToolbar上按钮无间隙等宽的需求！你当前按toolbar宽度均分按钮的思路是对的，但问题出在UIButton默认的内边距和UIBarButtonItem之间的默认间距上，咱们一步步调整：

步骤1：优化按钮的内边距 #

UIButton默认会给标题/图标留一些内边距，这会导致按钮看起来比预期窄，或者出现莫名间隙。创建按钮时，把这些内边距彻底清零：

- (UIButton *)createMenuButton:(NSString *)title width:(CGFloat)width height:(CGFloat)height {
    UIButton *btn = [UIButton buttonWithType:UIButtonTypeSystem];
    [btn setTitle:title forState:UIControlStateNormal];
    btn.frame = CGRectMake(0, 0, width, height);
    
    // 关键：清除所有内边距，让按钮内容填满整个frame
    btn.contentEdgeInsets = UIEdgeInsetsZero;
    btn.titleEdgeInsets = UIEdgeInsetsZero;
    btn.imageEdgeInsets = UIEdgeInsetsZero;
    // 强制内容居中，避免内边距调整导致偏移
    btn.contentHorizontalAlignment = UIControlContentHorizontalAlignmentCenter;
    btn.contentVerticalAlignment = UIControlContentVerticalAlignmentCenter;
    
    return btn;
}

步骤2：消除UIBarButtonItem之间的间距 #

UIToolbar的UIBarButtonItem默认会在item之间添加小间距，这里提供两种靠谱的解决方案：

方案A：用自定义容器View包装所有按钮 #

把四个按钮统一放到一个和toolbar同高的UIView里，再把这个View作为单个UIBarButtonItem的customView，彻底规避item之间的默认间距：

CGFloat toolbarWidth = self.toolbarMapMenu.frame.size.width;
CGFloat toolbarHeight = self.toolbarMapMenu.frame.size.height;
CGFloat buttonWidth = toolbarWidth / 4.0;

UIButton *btn0 = [self createMenuButton:@"a" width:buttonWidth height:toolbarHeight];
UIButton *btn1 = [self createMenuButton:@"b" width:buttonWidth height:toolbarHeight];
UIButton *btn2 = [self createMenuButton:@"c" width:buttonWidth height:toolbarHeight];
UIButton *btn3 = [self createMenuButton:@"d" width:buttonWidth height:toolbarHeight];

// 创建容器View，尺寸和toolbar完全一致
UIView *buttonContainer = [[UIView alloc] initWithFrame:CGRectMake(0, 0, toolbarWidth, toolbarHeight)];

// 逐个添加按钮到容器，精准设置x坐标
btn0.frame = CGRectMake(0, 0, buttonWidth, toolbarHeight);
[buttonContainer addSubview:btn0];

btn1.frame = CGRectMake(buttonWidth, 0, buttonWidth, toolbarHeight);
[buttonContainer addSubview:btn1];

btn2.frame = CGRectMake(buttonWidth * 2, 0, buttonWidth, toolbarHeight);
[buttonContainer addSubview:btn2];

btn3.frame = CGRectMake(buttonWidth * 3, 0, buttonWidth, toolbarHeight);
[buttonContainer addSubview:btn3];

// 把容器作为customView添加到toolbar
UIBarButtonItem *containerItem = [[UIBarButtonItem alloc] initWithCustomView:buttonContainer];
self.toolbarMapMenu.items = @[containerItem];

方案B：手动设置item宽度并插入0间距的Fixed Space #

如果不想用容器，也可以给每个UIBarButtonItem设置宽度，并且在item之间插入宽度为0的固定间距来抵消默认间隙：

CGFloat width = self.toolbarMapMenu.frame.size.width / 4.0;
CGFloat height = self.toolbarMapMenu.frame.size.height;

UIButton *btn0 = [self createMenuButton:@"a" width:width height:height];
UIButton *btn1 = [self createMenuButton:@"b" width:width height:height];
UIButton *btn2 = [self createMenuButton:@"c" width:width height:height];
UIButton *btn3 = [self createMenuButton:@"d" width:width height:height];

UIBarButtonItem *it0 = [[UIBarButtonItem alloc] initWithCustomView:btn0];
UIBarButtonItem *it1 = [[UIBarButtonItem alloc] initWithCustomView:btn1];
UIBarButtonItem *it2 = [[UIBarButtonItem alloc] initWithCustomView:btn2];
UIBarButtonItem *it3 = [[UIBarButtonItem alloc] initWithCustomView:btn3];

// 关键：设置每个item的宽度和按钮一致
it0.width = width;
it1.width = width;
it2.width = width;
it3.width = width;

// 创建0宽度的固定间距item，用来抵消默认间隙
UIBarButtonItem *zeroSpace = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFixedSpace target:nil action:nil];
zeroSpace.width = 0;

// 组装items：按钮 + 0间距 + 按钮...
self.toolbarMapMenu.items = @[it0, zeroSpace, it1, zeroSpace, it2, zeroSpace, it3];

额外提醒：适配尺寸变化 #

如果toolbar的宽度会动态变化（比如设备旋转），建议在viewWillLayoutSubviews方法里重新计算按钮宽度并更新布局，避免按钮错位或间隙重现。

内容的提问来源于stack exchange，提问作者Martin Perry