在IOS開發(fā)的過程中我們經(jīng)常會遇到一些緊貼tabbar有工具條之類的頁面河泳，比如說購買沃呢、支付等頁面，往往這些頁面有時候在棧底顯示（頁面有tabbar）拆挥，有時不在（頁面沒有tabbar）薄霜。比如：

shop.png

這種頁面對于常規(guī)的做法是有tabbar的時候設(shè)置一套約束，沒有tabbar的時候更新一下約束。但是蘋果提過了一個bottomLayoutGuide可以讓我們更優(yōu)雅的處理這類問題惰瓜。
代碼如下：

_bottomView = [UIView new];
    _bottomView.backgroundColor = [UIColor yellowColor];
    [self.view addSubview:_bottomView];
    [_bottomView mas_makeConstraints:^(MASConstraintMaker *make) {
        make.height.equalTo(@40);
        make.left.and.right.equalTo(self.view);
        make.bottom.equalTo(self.mas_bottomLayoutGuide);
    }];

搭配Masonry否副，使用Masonry提供的mas_bottomLayoutGuide僅需一行我們就可以實現(xiàn)這樣的效果。

同樣來說這種效果對于navigationBar也適用——topLayoutGuide崎坊。對應(yīng)的Masonry使用方法是mas_topLayoutGuide备禀。
完整代碼（代碼量太少就不給完整的鏈接了）：

#import "ViewController.h"
#import "Masonry.h"
@interface ViewController ()
@property (strong, nonatomic) UIView *topView;
@property (strong, nonatomic) UIView *bottomView;
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    UIButton *btn = [UIButton buttonWithType:UIButtonTypeCustom];
    btn.frame = CGRectMake(0, 164, 80, 50);
    [btn setTitle:@"top" forState:UIControlStateNormal];
    btn.backgroundColor = [UIColor redColor];
    [btn addTarget:self action:@selector(topClick) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:btn];
    
    UIButton *btn1 = [UIButton buttonWithType:UIButtonTypeCustom];
    btn1.backgroundColor = [UIColor yellowColor];
    btn1.frame = CGRectMake(0, 264, 80, 50);
    [btn1 setTitle:@"bottom" forState:UIControlStateNormal];
    [btn1 setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
    [btn1 addTarget:self action:@selector(bottomClick) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:btn1];
    [self initView];
}

- (void)initView {
    _topView = [UIView new];
    _topView.backgroundColor = [UIColor greenColor];
    [self.view addSubview:_topView];
    [_topView mas_makeConstraints:^(MASConstraintMaker *make) {
        make.height.equalTo(@40);
        make.left.and.right.equalTo(self.view);
        
        make.top.equalTo(self.mas_topLayoutGuide);
        
    }];
    
    _bottomView = [UIView new];
    _bottomView.backgroundColor = [UIColor yellowColor];
    [self.view addSubview:_bottomView];
    [_bottomView mas_makeConstraints:^(MASConstraintMaker *make) {
        make.height.equalTo(@40);
        make.left.and.right.equalTo(self.view);
        make.bottom.equalTo(self.mas_bottomLayoutGuide);
    }];
}
- (void)topClick{

    [self.navigationController setNavigationBarHidden:!self.navigationController.navigationBarHidden animated:NO];
//    [self updateViewConstraints];
}
- (void)bottomClick{
    
    [self.navigationController setToolbarHidden:!self.navigationController.toolbarHidden animated:NO];
    // 手動觸發(fā)updateViewConstraints
//    [self updateViewConstraints];
}
- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}


@end