最近有個項目需要自定義tabbar，
我自定義tabbar的一個思路就是完全取代系統自帶的tabbar，生成一個繼承自UIview的customTabbar，将生成的customTabbar完全覆寫到tabbar上，為了讓我們自己生成的tabbar也能使用系統的一些方法，我們需要将customTabbar添加到系統的tabbar上，這就是我的一個大概思路(後期再添加自定義的相關邏輯和代碼)
在自定義tabbar的時候出現的問題，在iOS7以後tabbar做了一些修改，如果我們将customTabbar直接添加到系統的tabbar後，我們會發現，在顯示的時候出現我們自己的tabbar和系統的tabbar這種效果當然使我們不需要的，怎麼解決呢？我提供一個我的思路：我的做法是将系統tabbar生成的UItabbarButton從他的父視圖上面移除，
for (UIView *button in self.tabBar.subviews) {
if ([button isKindOfClass:[LXQTabBar class]]) {
NSLog(@"button == %@",button);
} else {
[button removeFromSuperview];
}
}
這樣就完美解決了，但是在後期使用中又發現一個問題，當我們dismiss或則popToViewController的時候，還是會出現系統的tabbarbutton，什麼原因呢？我也不清楚，我大概想到可能和view裡面的layoutSubviews這個方法有關，（希望有大神能講解一下這一塊的東西，謝謝），但是tabbarController沒有這個方法，隻有viewwilllayoutsubviews和ViewWilldidlayoutsubsiews這兩個方法，最後将删除系統tabbarbutton的方法添加到了ViewWillLayoutSubviews這個方法裡面就解決了這個問題
後記：
在更新iOS 10以後又重新出現以前的情況，一時不知道該怎麼去解決，後面想了想，一直在外部去修改還不如去内部修改，是以想到了runtime來解決這個問題，通過runtime去修改系統的方法下面列出代碼：
一、列印UITabbar系統方法:
- (void)systemMethod{
unsigned int count;
NSMutableArray *array = [NSMutableArray array];
Method *meths = class_copyMethodList([UITabBar class], &count);
for (int i = 0; i < count; i ++) {
Method meth = meths[i];
SEL sel = method_getName(meth);
const char *name = sel_getName(sel);
NSString *str = [NSString stringWithFormat:@"-------------- > %s",name];
[array addObject:str];
}
LOG(@"%@",array);
}
列印的結果：
(
"-------------- > remove_layoutSubviews",
"-------------- > setDelegate:",
"-------------- > layoutSubviews",
"-------------- > _populateArchivedSubviews:",
"-------------- > hitTest:withEvent:",
"-------------- > _intrinsicSizeWithinSize:",
"-------------- > _contentHuggingDefault_isUsuallyFixedHeight",
"-------------- > sizeThatFits:",
"-------------- > traitCollectionDidChange:",
"-------------- > _backgroundView",
"-------------- > setSemanticContentAttribute:",
"-------------- > setTranslatesAutoresizingMaskIntoConstraints:",
"-------------- > touchesBegan:withEvent:",
"-------------- > touchesMoved:withEvent:",
"-------------- > touchesEnded:withEvent:",
"-------------- > touchesCancelled:withEvent:",
"-------------- > _setVisualAltitude:",
"-------------- > _setVisualAltitudeBias:",
"-------------- > isTranslucent",
"-------------- > isLocked",
"-------------- > didUpdateFocusInContext:withAnimationCoordinator:",
"-------------- > preferredFocusedItem",
"-------------- > setTintColor:",
"-------------- > _isEligibleForFocus",
"-------------- > canBecomeFocused",
"-------------- > removeConstraint:",
"-------------- > addConstraint:",
"-------------- > _didMoveFromWindow:toWindow:",
"-------------- > hitTest:forEvent:",
"-------------- > _didChangeFromIdiom:onScreen:traverseHierarchy:",
"-------------- > _subclassImplementsDrawRect",
"-------------- > backgroundImage",
"-------------- > shadowImage",
"-------------- > setShadowImage:",
"-------------- > _appearanceStorage",
"-------------- > _accessibilityButtonShapesParametersDidChange",
"-------------- > _effectiveBarTintColor",
"-------------- > setItems:animated:",
"-------------- > setLocked:",
"-------------- > setBarStyle:",
"-------------- > _hidesShadow",
"-------------- > _backdropViewLayerGroupName",
"-------------- > _setBackdropViewLayerGroupName:",
"-------------- > _shadowView",
"-------------- > _setBackgroundView:",
"-------------- > _shadowAlpha",
"-------------- > _setShadowAlpha:",
"-------------- > _disableBlurTinting",
"-------------- > _setDisableBlurTinting:",
"-------------- > setBarTintColor:",
"-------------- > _setHidesShadow:",
"-------------- > barStyle",
"-------------- > setTranslucent:",
"-------------- > barTintColor",
"-------------- > _accessoryView",
"-------------- > _isTranslucent",
"-------------- > _setBarOrientation:",
"-------------- > _setAccessoryView:",
"-------------- > setSelectedItem:",
"-------------- > _setPreferredFocusHeading:",
"-------------- > _setFocusedItemHightlightShouldBeVisible:",
"-------------- > _setHiddenAwaitingFocus:",
"-------------- > beginCustomizingItems:",
"-------------- > isCustomizing",
"-------------- > setBackgroundImage:",
"-------------- > _sendAction:withEvent:",
"-------------- > _barMetrics",
"-------------- > _imageStyle",
"-------------- > _setBarMetrics:",
"-------------- > _setImageStyle:",
"-------------- > selectionIndicatorImage",
"-------------- > selectedImageTintColor",
"-------------- > _effectiveUnselectedTabTintColorConsideringView:",
"-------------- > _buttonDown:",
"-------------- > _buttonUp:",
"-------------- > _buttonCancel:",
"-------------- > _showsHighlightedState",
"-------------- > _setShowsHighlightedState:",
"-------------- > _scrollsItems",
"-------------- > itemPositioning",
"-------------- > itemWidth",
"-------------- > itemSpacing",
"-------------- > _configureItems:",
"-------------- > _setBackgroundNeedsUpdate:",
"-------------- > _blurEnabled",
"-------------- > _preferredFocusHeading",
"-------------- > selectedItem",
"-------------- > _focusedItemHighlightShouldBeVisible",
"-------------- > _setBlurEnabled:",
"-------------- > setSelectionIndicatorImage:",
"-------------- > setSelectedImageTintColor:",
"-------------- > _configureTabBarReplacingItem:withNewItem:swapping:",
"-------------- > _positionAllItems",
"-------------- > setItemWidth:",
"-------------- > setItemSpacing:",
"-------------- > _setScrollsItems:",
"-------------- > setItemPositioning:",
"-------------- > _accessibilityButtonShapesEnabledDidChangeNotification:",
"-------------- > setUnselectedItemTintColor:",
"-------------- > _doCommonTabBarInit",
"-------------- > _effectiveBarOrientation",
"-------------- > _updateBackgroundColorForTraitCollection:",
"-------------- > _customizeWithAvailableItems:",
"-------------- > _dismissCustomizeSheet:",
"-------------- > _updateTintedImages:selected:",
"-------------- > _effectiveBarTintColorDidChange",
"-------------- > unselectedItemTintColor",
"-------------- > _effectiveUnselectedTintColor",
"-------------- > _isHiddenAwaitingFocus",
"-------------- > _buttonDownDelayed:",
"-------------- > _adjustButtonSelection:",
"-------------- > _customizeDoneButtonAction:",
"-------------- > _totalDimensionForItems:spacing:dimension:scaleFactor:",
"-------------- > _setBackgroundImage:",
"-------------- > _setSelectionIndicatorImage:",
"-------------- > _setLabelFont:",
"-------------- > _setLabelTextColor:selectedTextColor:",
"-------------- > _setLabelShadowColor:",
"-------------- > _setLabelShadowOffset:",
"-------------- > _setVibrantLabels:",
"-------------- > _vibrantLabels",
"-------------- > _nextSelectionSlideDuration",
"-------------- > _setNextSelectionSlideDuration:",
"-------------- > _backgroundNeedsUpdate",
"-------------- > _setTabBarSizing:",
"-------------- > _setTabButtonWidth:",
"-------------- > _tabButtonWidth",
"-------------- > _setInterTabButtonSpacing:",
"-------------- > _interTabButtonSpacing",
"-------------- > _barOrientation",
"-------------- > endCustomizingAnimated:",
"-------------- > _makeCurrentButtonFirstResponder",
"-------------- > _setDividerImage:forLeftButtonState:rightButtonState:",
"-------------- > _dividerImageForLeftButtonState:rightButtonState:",
"-------------- > _pendingFocusAction",
"-------------- > _setPendingFocusAction:",
"-------------- > _focusedTabBarItem",
"-------------- > _tabBarFinishedAnimating",
"-------------- > dismissCustomizeSheet:",
"-------------- > _scaleFactorForItems:spacing:dimension:maxWidth:",
"-------------- > _updateTabBarItemView:",
"-------------- > _tabBarSizing",
"-------------- > isElementAccessibilityExposedToInterfaceBuilder",
"-------------- > _autolayoutSpacingAtEdge:inContainer:",
"-------------- > _autolayoutSpacingAtEdge:nextToNeighbor:",
"-------------- > _hasCustomAutolayoutNeighborSpacing",
"-------------- > encodeWithCoder:",
"-------------- > initWithCoder:",
"-------------- > delegate",
"-------------- > setBounds:",
"-------------- > .cxx_destruct",
"-------------- > dealloc",
"-------------- > initWithFrame:",
"-------------- > setFrame:",
"-------------- > items",
"-------------- > setItems:",
"-------------- > drawRect:"
)
我接觸iOS的時間也不長，不能從這對堆結果中去找到具體設定tabbarbutton的方法，但是我知道layoutSubviews是布局子視圖的方法，然後就用runtime替換掉UItabbar中的layoutSubviews方法，在布局子視圖的時候将系統自帶的UItabbarbutton給移除掉，貼代碼:
這段代碼是寫在UItabbar的分類中的:
+ (void)load{
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
SEL systemSel = @selector(layoutSubviews);
SEL lxqSel = @selector(remove_layoutSubviews);
Method systemMethod = class_getInstanceMethod([self class], systemSel);
Method lxqMethod = class_getInstanceMethod([self class], lxqSel);
BOOL isAdd = class_addMethod(self, systemSel, method_getImplementation(lxqMethod), method_getTypeEncoding(lxqMethod));
if (isAdd) {
class_replaceMethod(self, lxqSel, method_getImplementation(systemMethod), method_getTypeEncoding(systemMethod));
} else {
method_exchangeImplementations(systemMethod, lxqMethod);
}
});
}
- (void)remove_layoutSubviews{
NSArray *subviews = self.subviews;
for (UIView *subview in subviews) {
if ([subview isKindOfClass:[LXQTabBar class]]) {
} else {
[subview removeFromSuperview];
}
}
}
這樣就完美解決了iOS10 以及以前系統的問題了，不過就是不知道這樣做了之後會不會出現稽核不通過的問題！
![自定義帶加号的tabBar[圖]](data:image/gif;base64,R0lGODlhAQABAIAAAP///wAAACwAAAAAAQABAAACAkQBADs=)