这是我代码

UIToolbar *toolbar = [[UIToolbar alloc] initWithFrame:CGRectMake(0, 200, UIScreen.mainScreen.bounds.size.width, 44)];
self.toolbar = boolbar;
[self.view addSubview:toolbar];

NSMutableArray *arrayM = [NSMutableArray array];
NSArray *titles = @[@"title0", @"title1", @"title2", @"title3"];
for (int i = 0; i < titles.count; i++) {
    [arrayM addObject:[[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace] target:nil action:nil];

    UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
    button.backgroundColor = [UIColor colorWithRed:arc4random_uniform(256)/255.0 green:arc4random_uniform(256)/255.0 blue:arc4random_uniform(256)/255.0 alpha:1.0];
    [button setTitle:titles[i] forState:UIControlStateNormal];
    UIBarButtonItem *item = [[UIBarButtonItem alloc] initWithCustomView:button];
    [arrayM addObject:item];
}
[arrayM addObject:[[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace] target:nil action:nil];
toolbar.items = arrayM;

结果如下图screenshot所示
按钮的可点击范围太小，我不想给按钮设置固定大小，因为按钮标题会不一样。我想让每个按钮在工具栏上均匀分布，但我找不到合适的方法
我尝试使用系统提供的所有项目，但没有任何工作
all UIBarButtonSystemItem