GitHub上的代码已经更新（2017-09-28），请不要copy文中代码，代码有遗漏！！！！
另外，请特别注意，本套类扩展只能在Xcode9以上的版本中使用，在Xcode9以前的开发环境中编译打包都没问题，但 APP在iOS 11中运行会奔溃！！！！
注意：
截止目前(2017-09-28)代码已经发生两次更新，适配解决思路已经发生变化，原来旧文章中的解决方式，会碰到如下问题：
1. iOS 11下，进入一个添加了导航栏按钮的页面起初是正常的，当push到下一个页面再pop回来时，会发现原来设置好的间距又失效了；
2. UIBarButtonItem被添加到UIToolBar时有问题，严重时闪退；
3. 通过initWithBarButtonSystemItem:target:action:方法创建的item不能实现布局适配；
更新记录：
版本1.2（2017-09-28）
- 替换UIBarButtonItem原生实例化方法initWithBarButtonSystemItem:target:action:（最新版本中，stone哥自己用ps抠了一套SystemItem的icon图，不是很精细，毕竟stone哥的强项是敲代码，如有用到该方法创建item，建议要自己家的美工做一套图来替换）
- 替换UIBarButtonItem原生的setTarget: 和 setAction: 方法；
- 解决popBack后，约束失效的问题，添加约束的位置发生变化，新增UIStackView的类扩展，在其layoutSoubviews方法中实现约束条件的设置；
版本1.1（2017-09-26）
- 增加UIBarButtonItem被添加到UIToolbar上的处理；
- 增加对UIBarButtonItem的UIBarButtonItemStyleDone类型的解析；
对实现方式进行的修改做一点解释：
- 在iOS 11中，UINavigationBar上有个contentView，contentView的两边各有个stackView，分别用于渲染左右两边添加的UIBarButtonItem；
- 从一个页面push到另一个页面完成时，前一个页面，contentView上两边的stackView都会被移除并销毁；
- 页面将要pop回去时，会实例化两个新的stackView用于承载前一个页面的Item;
这就是为什么pop回去后，原来添加的约束条件失效了，因为这个时候stackView已经是一个新的对象了，并没有对其添加约束，所以解决思路变成了在stackView 的 layoutSubViews方法里进行约束设置。
想了解整个适配思路的演变，请看以下最初文章初稿，看思路，看知识点，代码有误，请download源码。 (2017-09-22)
最新版Xcode9在20号已经提供下载了，Stone哥哥作为一个凡事喜欢走在前面的人（不要脸了，哈哈哈，不过Stone哥哥的手机系统确实是从iOS 11第一个beta版开始使用的，体验过各种bug煎熬，终于熬到正式版了，内牛满面...），当然第一时间就升级了，下载安装完5个多鸡的安装包，Stone哥哥激动的打开了目前正在开发的项目，Command+B，成功编译！但是当我点击运行，在APP中跳转几个页面后，忽然注意到导航栏...WTF!!!
WTF.png
这间距可就大得有点惊人哈，顿时把Stone哥哥脸都吓白了...
于是Stone哥哥赶紧把原来用于调整间距的BarButton的负宽度一口气调到-50，[UIBarButtonItem zg_fixedSpaceWithWidth:-50];
+ (UIBarButtonItem *)zg_fixedSpaceWithWidth:(CGFloat)width {
UIBarButtonItem *spaceBarButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFixedSpace
target:nil
action:nil];
spaceBarButton.width = width;
return spaceBarButton;
}
然鹅...这 并没什么卵用！并没什么卵用！并没什么卵用！
有点意思，就喜欢可以折腾一番的问题，所以我们还是和以往一样，从发现问题开始，冷静滴一步一步来把问题攻破。
一. 找出布局错乱的原因
既然老一套调整间距的方式已经不起作用，那要么iOS 11增加了一种新的用于调整间距的UIBarButtonItem类型，要么就是整个解析发生变更，图层有变化，看图层是否有变化这个最直观又方便，所以我们先对图层来一探究竟
iOS 11的NavBar布局.png
这是最新的iOS 11导航栏的视图层级结构，好复杂的样子，一个小小的item，叠了这么多层级，而且使用了autoLayout来布局，虽然图层很多，但看起来也很合理的样子，而且基本上就可以确定对item间距的调整方向——更改layout约束条件。忘了iOS 11以前是什么样子了，但感觉有变化，所以我们再来看看iOS 11以前的视图层级结构
iOS 11以前系统导航栏视图层级结构.png
还真是不一样，很显然，iOS 11以前系统导航栏的层级结构好简单很多，而且没有使用autoLayout。所有的视图都堆在UINavigationBar上，对比起来，老版本确实不是很合理的样子，心里默默为这个细小的优化点个赞！
新版本的调整方向已经确定了，那能不能让老版本也统一呢，也给UINavigationButton也加上约束条件，抛弃fixedSpace类型的UIBarButtonItem。然鹅，这种操作是被禁止的，程序会无情的crash
不能给NavigationBar添加约束.png
苹果不允许开发者给UINavigationBar添加约束...
唉！没事，坚强的Stone哥并没有哭，那就分开两种不同的适配方式吧，那我们再来对iOS 11以前的老版本的渲染规则好好了解一番，从前面图“iOS 11以前系统导航栏视图层级结构.png”和Stone哥的一番测试，得出了一下一些结论：
- 系统自己创建的UINavigationButton内含的图片和标题水平和垂直方向都是居中对齐；
- UINavigationButton高度上没有撑满整个UINavigationBar的高度，并且没有居中对齐，图中右边的两个item就很明显没在垂直方向对齐；
- 另外经过一点点微调，UINavigationButton左右两边与屏幕边缘的距离都是15，右边的两个item间距大概为5，固定不可调整；
看到这里，你可能跟我一样想吐槽了，原来iOS 11以前的系统导航栏渲染是这么随意，这里辣鸡...哈哈哈，所以Stone哥得好好的拯救他一下。
现在问题的根源了解得差不多了，也基本有了解决思路，所以是时候进入解决问题的第二步了。
二. 解题思路
1. 针对老版本：
看到老版本中，系统从UIBarButtonItem到添加到UINavigationBar上的UINavigationButton的转化如此糟糕，而且想要再对其进行修改极其困难，决定要阻断这一层转换，全都创建自己的CustomView，并对其进行对其设置，即添加到左边则左对齐，右边则右对齐，并且高度撑满整个导航栏，总之就是这个customView要弥补前面提到的老版本的所有不足。
2. 针对新版本：
前面已经提到，新版本通过改变约束来实现调整，但是具体在什么时候，在哪个地方来调整呢，首先我想到在[UINavigationBar layoutSubviews] 方法里遍历subViews来设置约束，但是subViews里最终遍历到UIStackView的时候，并没有position信息，即不知道这个视图是被添加在了左边还是右边，所以很显然也会需要CustomView，并在其中包含位置信息，既然这样，何不将改变约束的方法放在CustomView的layoutSubviews里呢，减少对一个系统类的修改应该是降低风险降低复杂度的操作吧，哈哈，要在CustomView里设置约束的话，那CustomView还需要包含另外一条信息，就是与它相邻的另外一个CustomView，因为要设置两两之间的间距。
- 到这里，我们的主角CustomView类就有了两个必须的属性了，一个描述被添加的位置(左或右)的position，一个指向前一个相邻CustomView的属性prevCustomView；
- 另外要阻断系统对UIBarButtonItem的转换，CustomView还应该增加几个和UIBarButtonItem对应的实例化方法，最终得到了CustomView类的声明如下
#import <UIKit/UIKit.h>
typedef NS_ENUM(NSInteger, ZGBarButtonItemPosition) {
ZGBarButtonItemPositionLeft,
ZGBarButtonItemPositionRight
};
typedef NS_ENUM(NSInteger, ZGBarButtonItemType) {
ZGBarButtonItemTypeTitle,
ZGBarButtonItemTypeImage,
ZGBarButtonItemTypeCustomView
};
@interface ZGBarButtonItemCustomView : UIView
@property (nonatomic, assign) ZGBarButtonItemPosition position;
@property (nonatomic, weak) ZGBarButtonItemCustomView *prevCustomView;
@property (nonatomic, assign) ZGBarButtonItemType itemType;
- (instancetype)initWithTitle:(NSString *)title target:(id)target action:(SEL)action;
- (instancetype)initWithImage:(UIImage *)image target:(id)target action:(SEL)action;
- (instancetype)initWithCustomView:(UIView *)customView;
@end
- 针对老版本，CustomView 设置对其方式，自适应大小；
- 针对新版本，CustomView要设置约束；
- 因为需要添加响应，所以CustomView上应该添加一个button；
- 另外由于CustomView上的button的图片和文字正常情况下无法随UINavigationBar的tintColor改变，所以还得设置跟随tintColor，图片好说，本身的renderMode渲染模式就支持跟随tintColor改变，但是titleLabel不能，所以还要设置KVO监听UINavigationBar.tintColor的改变，随时更改titleLabel.textColor。
所以得到CustomView的实现代码如下：
#import "ZGBarButtonItemCustomView.h"
#import "UIView+ZGLayoutConstraint.h"
#import "ZGNavBarItemSpceMacro.h"
@interface ZGBarButtonItemCustomView ()
@property (nonatomic, strong) UIButton *button;
@property (nonatomic, assign) BOOL fixed;
@property (nonatomic, assign) BOOL isLastItem;
@property (nonatomic, weak) UINavigationBar *navBar;
@end
@implementation ZGBarButtonItemCustomView
- (instancetype)initWithTitle:(NSString *)title target:(id)target action:(SEL)action {
if (self = [super init]) {
[self p_setUpButtonWithTitle:title
image:nil
target:target
action:action];
[self p_init];
self.itemType = ZGBarButtonItemTypeTitle;
}
return self;
}
- (instancetype)initWithImage:(UIImage *)image target:(id)target action:(SEL)action {
if (self = [super init]) {
[self p_setUpButtonWithTitle:nil
image:image
target:target
action:action];
[self p_init];
self.itemType = ZGBarButtonItemTypeImage;
}
return self;
}
- (instancetype)initWithCustomView:(UIView *)customView {
if (self = [super init]) {
[self addSubview:customView];
[self setFrame:customView.bounds];
[self setCenter:customView.center];
[self p_init];
self.itemType = ZGBarButtonItemTypeCustomView;
}
return self;
}
- (void)dealloc {
[self.navBar removeObserver:self forKeyPath:@"tintColor"];
}
- (void)layoutSubviews {
[super layoutSubviews];
if ([[UIDevice currentDevice] systemVersion].floatValue < 11) {
[self p_setTitleFollowNavBarTintColorFromView:self];
return;
}
if (self.fixed) {
return;
}
UIView *adaptorView = [self p_getAdaptorViewFromView:self];
UIView *prevAdaptorView = [self p_getAdaptorViewFromView:self.prevCustomView];
[adaptorView zg_addSizeConstraintWithSize:self.frame.size];
[adaptorView zg_addCenterYConstraint];
CGFloat screenBorderGap = ZG_BAR_ITEM_SCREEN_BORDER_GAP;
if (self.position == ZGBarButtonItemPositionLeft) {
if (!prevAdaptorView) {
[adaptorView zg_addLeftBorderGap:0];
} else {
[prevAdaptorView zg_addHorizontalGap:ZG_BAR_ITEM_GAP toView:adaptorView];
}
if (self.isLastItem) {
UIStackView *stackView = [self p_getStackViewFromView:adaptorView];
for (NSLayoutConstraint *constraint in stackView.superview.constraints) {
if ([constraint.firstItem isKindOfClass:[UILayoutGuide class]] &&
constraint.firstAttribute == NSLayoutAttributeLeading) {
[stackView.superview removeConstraint:constraint];
}
}
if (self.itemType == ZGBarButtonItemTypeImage) {
screenBorderGap -= ZG_BAR_ITEM_LEFT_ICON_EDGE_INSETS;
}
[stackView zg_addLeftBorderGap:screenBorderGap];
}
} else if (self.position == ZGBarButtonItemPositionRight) {
if (!prevAdaptorView) {
[adaptorView zg_addRightBorderGap:0];
} else {
[adaptorView zg_addHorizontalGap:-ZG_BAR_ITEM_GAP toView:prevAdaptorView];
}
if (self.isLastItem) {
UIStackView *stackView = [self p_getStackViewFromView:adaptorView];
for (NSLayoutConstraint *constraint in stackView.superview.constraints) {
if ([constraint.firstItem isKindOfClass:[UILayoutGuide class]] &&
constraint.firstAttribute == NSLayoutAttributeTrailing) {
[stackView.superview removeConstraint:constraint];
}
}
if (self.itemType == ZGBarButtonItemTypeImage) {
screenBorderGap -= ZG_BAR_ITEM_RIGHT_ICON_EDGE_INSETS;
}
[stackView zg_addRightBorderGap:-screenBorderGap];
}
}
[self p_setTitleFollowNavBarTintColorFromView:adaptorView];
self.fixed = YES;
}
#pragma mark - KVO
- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary<NSKeyValueChangeKey,id> *)change context:(void *)context {
[self.button setTitleColor:self.navBar.tintColor forState:UIControlStateNormal];
}
#pragma mark - private
- (void)p_init {
self.isLastItem = YES;
self.fixed = NO;
self.position = ZGBarButtonItemPositionLeft;
}
- (void)p_setUpButtonWithTitle:(NSString *)title image:(UIImage *)image target:(id)target action:(SEL)action {
[self setButton:[[UIButton alloc] init]];
[self addSubview:self.button];
[self.button setTitleColor:[UIColor blueColor] forState:UIControlStateNormal];
[self.button setTintColor:[UIColor blueColor]];
[self.button setTitle:title forState:UIControlStateNormal];
[self.button.titleLabel setFont:ZG_BAR_ITEM_FONT];
if (image.renderingMode == UIImageRenderingModeAutomatic) {
image = [image imageWithRenderingMode:UIImageRenderingModeAlwaysTemplate];
}
[self.button setImage:image forState:UIControlStateNormal];
[self.button sizeToFit];
[self.button setFrame:CGRectMake(0, 0, MAX(self.button.frame.size.width, ZG_BAR_ITEM_MIN_WIDTH), 44)];
[self.button addTarget:target action:action forControlEvents:UIControlEventTouchUpInside];
[self setFrame:self.button.bounds];
}
- (UIView *)p_getAdaptorViewFromView:(UIView *)view {
if (!view) {
return nil;
}
UIView *tempView = view;
while (![tempView isKindOfClass:NSClassFromString(@"_UITAMICAdaptorView")] && tempView.superview) {
tempView = tempView.superview;
}
return tempView;
}
- (UIStackView *)p_getStackViewFromView:(UIView *)view {
if (!view) {
return nil;
}
UIView *tempView = view;
while (![tempView isKindOfClass:UIStackView.class] && tempView.superview) {
tempView = tempView.superview;
}
return (UIStackView *)tempView;
}
- (UINavigationBar *)p_getNavBarViewFromView:(UIView *)view {
if (!view) {
return nil;
}
UIView *tempView = view;
while (![tempView isKindOfClass:UINavigationBar.class] && tempView.superview) {
tempView = tempView.superview;
}
return (UINavigationBar *)tempView;
}
- (void)p_setTitleFollowNavBarTintColorFromView:(UIView *)view {
if (self.itemType == ZGBarButtonItemTypeTitle) {
self.navBar = [self p_getNavBarViewFromView:view];
[self.button setTitleColor:self.navBar.tintColor forState:UIControlStateNormal];
[self.navBar addObserver:self
forKeyPath:@"tintColor"
options:NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld
context:nil];
}
}
#pragma mark - setter & getter
- (void)setPosition:(ZGBarButtonItemPosition)position {
_position = position;
if (self.position == ZGBarButtonItemPositionLeft) {
[self.button setContentHorizontalAlignment:UIControlContentHorizontalAlignmentLeft];
} else {
[self.button setContentHorizontalAlignment:UIControlContentHorizontalAlignmentRight];
}
}
- (void)setPrevCustomView:(ZGBarButtonItemCustomView *)prevCustomView {
_prevCustomView = prevCustomView;
self.prevCustomView.isLastItem = NO;
}
@end
最后一步就是选择在合适的创建CustomView，和给CustomView设置其他属性了，这个很显然要分别给UIBarButtonItem和UINavigationItem写扩展，切面替换相关方法了，直接上代码：
UIBarButtonItem+ZGFixSpace.h
#import <UIKit/UIKit.h>
#import "ZGBarButtonItemCustomView.h"
@interface UIBarButtonItem (ZGFixSpace)
/*
* used before iOS 11
*/
+ (UIBarButtonItem *)zg_fixedSpaceWithWidth:(CGFloat)width;
/*
* the side the item be added in (left or right)
* used after iOS 11
*/
- (void)zg_setPosition:(ZGBarButtonItemPosition)position;
/*
* is the first itme at the current side
* used after iOS 11
*/
- (void)zg_setPrevCustomView:(ZGBarButtonItemCustomView *)prevCustomView;
@end
UIBarButtonItem+ZGFixSpace.m
#import "UIBarButtonItem+ZGFixSpace.h"
#import "NSObject+ZGRuntime.h"
@implementation UIBarButtonItem (ZGFixSpace)
+ (UIBarButtonItem *)zg_fixedSpaceWithWidth:(CGFloat)width {
UIBarButtonItem *spaceBarButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFixedSpace
target:nil
action:nil];
spaceBarButton.width = width;
return spaceBarButton;
}
+ (void)load {
[self zg_swizzleInstanceMethodWithOriginSel:@selector(initWithTitle:style:target:action:)
swizzledSel:@selector(zg_initWithTitle:style:target:action:)];
[self zg_swizzleInstanceMethodWithOriginSel:@selector(initWithImage:style:target:action:)
swizzledSel:@selector(zg_initWithImage:style:target:action:)];
[self zg_swizzleInstanceMethodWithOriginSel:@selector(initWithCustomView:)
swizzledSel:@selector(zg_initWithCustomView:)];
}
- (void)zg_setPosition:(ZGBarButtonItemPosition)position {
ZGBarButtonItemCustomView *zgCustomView = (ZGBarButtonItemCustomView *)self.customView;
zgCustomView.position = position;
}
- (void)zg_setPrevCustomView:(ZGBarButtonItemCustomView *)prevCustomView {
ZGBarButtonItemCustomView *zgCustomView = (ZGBarButtonItemCustomView *)self.customView;
zgCustomView.prevCustomView = prevCustomView;
}
- (instancetype)zg_initWithTitle:(NSString *)title style:(UIBarButtonItemStyle)style target:(id)target action:(SEL)action {
ZGBarButtonItemCustomView *zgCustomView = [[ZGBarButtonItemCustomView alloc] initWithTitle:title
target:target
action:action];
return [self zg_initWithCustomView:zgCustomView];
}
- (instancetype)zg_initWithImage:(UIImage *)image style:(UIBarButtonItemStyle)style target:(id)target action:(SEL)action {
ZGBarButtonItemCustomView *zgCustomView = [[ZGBarButtonItemCustomView alloc] initWithImage:image
target:target
action:action];
return [self zg_initWithCustomView:zgCustomView];
}
- (instancetype)zg_initWithCustomView:(UIView *)customView {
ZGBarButtonItemCustomView *zgCustomView = [[ZGBarButtonItemCustomView alloc] initWithCustomView:customView];
return [self zg_initWithCustomView:zgCustomView];
}
@end
这个扩展主要任务是实现前面说的，阻断系统从UIBarButtonItem到UINavigationButton的转换，实现手段为替换掉
UIBarButtonItem的三个实例化方法，在这三个方法中均创建一个CustomView，然后调用原生的initWithCustomView:方法，最终将这个CustomView渲染到UINavigationBar上，这样不会再有UINavigationButton的存在了。
接下来是 UINavigationItem+ZGFixSpace
这个扩展是替换掉在UIViewController中，给viewController.navigationItem添加item的四个方法，给每个item.customView完善前面讲到的position和prevCustomView两个属性，并针对iOS 11以前的版本，在item前添加一个用于调整与屏幕边缘间距的弹簧item，最终就能实现各个版本一样的自适应调整间距的效果。
#import "UINavigationItem+ZGFixSpace.h"
#import "NSObject+ZGRuntime.h"
#import "UIBarButtonItem+ZGFixSpace.h"
#import "ZGNavBarItemSpceMacro.h"
@implementation UINavigationItem (ZGFixSpace)
+ (void)load {
[self zg_swizzleInstanceMethodWithOriginSel:@selector(setLeftBarButtonItem:)
swizzledSel:@selector(zg_setLeftBarButtonItem:)];
[self zg_swizzleInstanceMethodWithOriginSel:@selector(setLeftBarButtonItems:)
swizzledSel:@selector(zg_setLeftBarButtonItems:)];
[self zg_swizzleInstanceMethodWithOriginSel:@selector(setRightBarButtonItem:)
swizzledSel:@selector(zg_setRightBarButtonItem:)];
[self zg_swizzleInstanceMethodWithOriginSel:@selector(setRightBarButtonItems:)
swizzledSel:@selector(zg_setRightBarButtonItems:)];
}
- (void)zg_setLeftBarButtonItem:(UIBarButtonItem *)leftBarButtonItem {
if (!leftBarButtonItem || [leftBarButtonItem isKindOfClass:[NSNull class]]) {
[self zg_setLeftBarButtonItem:nil];
return;
}
if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 11) {
[leftBarButtonItem zg_setPosition:ZGBarButtonItemPositionLeft];
[self zg_setLeftBarButtonItem:leftBarButtonItem];
} else {
[self setLeftBarButtonItems:@[leftBarButtonItem]];
}
}
- (void)zg_setLeftBarButtonItems:(NSArray *)leftBarButtonItems {
if (!leftBarButtonItems || [leftBarButtonItems isKindOfClass:[NSNull class]] || leftBarButtonItems.count == 0) {
[self zg_setLeftBarButtonItems:nil];
return;
}
NSMutableArray *items = [NSMutableArray array];
if ([[[UIDevice currentDevice] systemVersion] floatValue] < 11) {
ZGBarButtonItemCustomView *customView = (ZGBarButtonItemCustomView *)((UIBarButtonItem *)[leftBarButtonItems firstObject]).customView;
CGFloat gap = ZG_BAR_ITEM_SCREEN_BORDER_GAP;
if (customView.itemType == ZGBarButtonItemTypeImage) {
gap -= ZG_BAR_ITEM_LEFT_ICON_EDGE_INSETS;
}
[items addObject:[UIBarButtonItem zg_fixedSpaceWithWidth:-(15 - gap)]];
}
ZGBarButtonItemCustomView *prevCustomeView = nil;
for (NSInteger i=0; i<leftBarButtonItems.count; i++) {
UIBarButtonItem *item = [leftBarButtonItems objectAtIndex:i];
[item zg_setPosition:ZGBarButtonItemPositionLeft];
[items addObject:item];
[item zg_setPrevCustomView:prevCustomeView];
prevCustomeView = (ZGBarButtonItemCustomView *)item.customView;
}
[self zg_setLeftBarButtonItems:items];
}
- (void)zg_setRightBarButtonItem:(UIBarButtonItem *)rightBarButtonItem {
if (!rightBarButtonItem || [rightBarButtonItem isKindOfClass:[NSNull class]]) {
[self zg_setRightBarButtonItem:nil];
return;
}
if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 11) {
[rightBarButtonItem zg_setPosition:ZGBarButtonItemPositionRight];
[self zg_setRightBarButtonItem:rightBarButtonItem];
} else {
[self setRightBarButtonItems:@[rightBarButtonItem]];
}
}
- (void)zg_setRightBarButtonItems:(NSArray *)rightBarButtonItems {
if (!rightBarButtonItems || [rightBarButtonItems isKindOfClass:[NSNull class]] || rightBarButtonItems.count == 0) {
[self zg_setRightBarButtonItems:nil];
return;
}
NSMutableArray *items = [NSMutableArray array];
if ([[[UIDevice currentDevice] systemVersion] floatValue] < 11) {
ZGBarButtonItemCustomView *customView = (ZGBarButtonItemCustomView *)((UIBarButtonItem *)[rightBarButtonItems firstObject]).customView;
CGFloat gap = ZG_BAR_ITEM_SCREEN_BORDER_GAP;
if (customView.itemType == ZGBarButtonItemTypeImage) {
gap -= ZG_BAR_ITEM_RIGHT_ICON_EDGE_INSETS;
}
[items addObject:[UIBarButtonItem zg_fixedSpaceWithWidth:-(15 - gap)]];
}
ZGBarButtonItemCustomView *prevCustomeView = nil;
for (NSInteger i=0; i<rightBarButtonItems.count; i++) {
UIBarButtonItem *item = [rightBarButtonItems objectAtIndex:i];
[item zg_setPosition:ZGBarButtonItemPositionRight];
[item zg_setPrevCustomView:prevCustomeView];
prevCustomeView = (ZGBarButtonItemCustomView *)item.customView;
[items addObject:item];
}
[self zg_setRightBarButtonItems:items];
}
@end
另外还有两个工具类扩展
第一个 NSObject+ZGRuntime，主要是给实例对象添加了一个交换实例方法的API，前面的两个扩展都是在+ (void)load 方法里调用这个方法来替换掉原生API。
- (void)zg_swizzleInstanceMethodWithOriginSel:(SEL)originSel swizzledSel:(SEL)swizzledSel {
Method m1 = class_getInstanceMethod([self class], originSel);
Method m2 = class_getInstanceMethod([self class], swizzledSel);
method_exchangeImplementations(m1, m2);
}
第二个 UIView+ZGLayoutConstraint，这个扩展主要是提供了给View添加 尺寸(size)，Y坐标中心点(centerY)，与另一个view的水平间距(horizontalGap)，与父视图边缘间距等的约束的API，在CustomView类的layoutSubviews方法里，iOS 11以后的导航栏就是调用这些方法来添加约束。
#import "UIView+ZGLayoutConstraint.h"
@implementation UIView (ZGLayoutConstraint)
- (void)zg_addSizeConstraintWithSize:(CGSize)size {
[self addConstraint:[NSLayoutConstraint constraintWithItem:self
attribute:NSLayoutAttributeWidth
relatedBy:NSLayoutRelationEqual
toItem:nil
attribute:NSLayoutAttributeNotAnAttribute
multiplier:1.0
constant:size.width]];
[self addConstraint:[NSLayoutConstraint constraintWithItem:self
attribute:NSLayoutAttributeHeight
relatedBy:NSLayoutRelationEqual
toItem:nil
attribute:NSLayoutAttributeNotAnAttribute
multiplier:1.0
constant:size.height]];
}
- (void)zg_addCenterYConstraint {
[self.superview addConstraint:[NSLayoutConstraint constraintWithItem:self
attribute:NSLayoutAttributeCenterY
relatedBy:NSLayoutRelationEqual
toItem:self.superview
attribute:NSLayoutAttributeCenterY
multiplier:1.0
constant:0]];
}
- (void)zg_addHorizontalGap:(CGFloat)gap toView:(UIView *)view {
[self.superview addConstraint:[NSLayoutConstraint constraintWithItem:self
attribute:NSLayoutAttributeRight
relatedBy:NSLayoutRelationEqual
toItem:view
attribute:NSLayoutAttributeLeft
multiplier:1.0
constant:gap]];
}
- (void)zg_addLeftBorderGap:(CGFloat)gap {
[self.superview addConstraint:[NSLayoutConstraint constraintWithItem:self
attribute:NSLayoutAttributeLeading
relatedBy:NSLayoutRelationEqual
toItem:self.superview
attribute:NSLayoutAttributeLeading
multiplier:1.0
constant:gap]];
}
- (void)zg_addRightBorderGap:(CGFloat)gap {
[self.superview addConstraint:[NSLayoutConstraint constraintWithItem:self
attribute:NSLayoutAttributeTrailing
relatedBy:NSLayoutRelationEqual
toItem:self.superview
attribute:NSLayoutAttributeTrailing
multiplier:1.0
constant:gap]];
}
@end
最后，也是最重要的，是便于开发者设置间距的宏文件 ZGNavBarItemSpceMacro
#ifndef ZGNavBarItemSpceMacro_h
#define ZGNavBarItemSpceMacro_h
#define ZG_BAR_ITEM_SCREEN_BORDER_GAP 10 // item到屏幕边缘的距离
#define ZG_BAR_ITEM_GAP 5 // item之间的距离 ios11以后生效
#define ZG_BAR_ITEM_LEFT_ICON_EDGE_INSETS 6 // 左边item图标图片内边距
#define ZG_BAR_ITEM_RIGHT_ICON_EDGE_INSETS 2 // 右边item图标图片内边距
#define ZG_BAR_ITEM_MIN_WIDTH 44 // item的最小宽度
#define ZG_BAR_ITEM_FONT [UIFont systemFontOfSize:15 weight:UIFontWeightLight] // item字体 ios11以后生效
#endif /* ZGNavBarItemSpceMacro_h */
好啦，全部干活已出，感谢阅读，欢迎去GitHub下载并点星星，爱你哟！！！
