方法一
在当前页面加入下面方法
- (void)viewWillAppear:(BOOL)animated{
[superviewWillAppear:animated];
[self.navigationController.navigationBarsetBackgroundImage:[UIImagenew]forBarMetrics:UIBarMetricsDefault];
//去掉导航栏底部的黑线
self.navigationController.navigationBar.shadowImage = [UIImage new];
}
如果仅设置当前页导航透明，需加入下面方法- (void)viewWillDisappear:(BOOL)animated{
[superviewWillDisappear:animated];
[self.navigationController.navigationBarsetBackgroundImage:nilforBarMetrics:UIBarMetricsDefault];
[self.navigationController.navigationBarsetShadowImage:nil];
}
方法二(这个方法在iOS 11上会出现crash,iOS 11上[self.navigationController.navigationBar subviews]值为空)
- (void)viewWillAppear:(BOOL)animated{
[superviewWillAppear:animated];
[[self.navigationController.navigationBar subviews]objectAtIndex:0].alpha =0;
}
仅设置当前页面
- (void)viewWillDisappear:(BOOL)animated{
[super viewWillDisappear:animated];
[[self.navigationController.navigationBar subviews]objectAtIndex:0].alpha =1;
}
我这有一个很好的三方库：
@property (nonatomic, strong) UIColor *barColor; //NavigationBar background color, default is white
@property (nonatomic, strong) UIColor *tintColor; //NavigationBar subviews color
@property (nonatomic, strong) UIImage *backgroundImage; //default is nil
@property (nonatomic, assign) UIStatusBarStyle statusBarStyle; // default is UIStatusBarStyleDefault
@property (nonatomic, assign) float zeroAlphaOffset;//color will changed begin this offset, default is -64
@property (nonatomic, assign) float fullAlphaOffset;//color alpha will be 1 in this offset, default is 200
@property (nonatomic, assign) float minAlphaValue;//bar minAlpha, default is 0
@property (nonatomic, assign) float maxAlphaValue;//bar maxAlpha, default is 1
@property (nonatomic, strong) UIColor *fullAlphaTintColor;//if you set this property, the tintColor will changed in fullAlphaOffset
@property (nonatomic, assign) UIStatusBarStyle fullAlphaBarStyle;//if you set this property, the barStyle will changed in fullAlphaOffset
@property (nonatomic, assign) BOOL allChange;//if allchange = yes, the tintColor will changed with the barColor change, default is yes, if you only want to change barColor, set allChange = NO
@property (nonatomic, assign) BOOL reversal;//this will cause that if currentAlpha = 0.3,it will be 1 - 0.3 = 0.7
@property (nonatomic, assign) BOOL continues;//when continues = YES, bar color will changed whenever you scroll, if you set continues = NO,it only be changed in the fullAlphaOffset
+ (void)setBarColor:(UIColor *)color;
+ (void)setTintColor:(UIColor *)color;
+ (void)setBackgroundImage:(UIImage *)image;
+ (void)setStatusBarStyle:(UIStatusBarStyle)style;
+ (void)setZeroAlphaOffset:(float)offset;
+ (void)setFullAlphaOffset:(float)offset;
+ (void)setMaxAlphaValue:(float)value;
+ (void)setMinAlphaValue:(float)value;
+ (void)setFullAlphaTintColor:(UIColor *)color;
+ (void)setFullAlphaBarStyle:(UIStatusBarStyle)style;
+ (void)setAllChange:(BOOL)allChange;
+ (void)setReversal:(BOOL)reversal;
+ (void)setContinues:(BOOL)continues;
+ (void)managerWithController:(UIViewController *)viewController;//you should use this method to init MXNavigationManager
+ (void)changeAlphaWithCurrentOffset:(CGFloat)currentOffset;// implemention this method in @selectot(scrollView: scrollViewDidScroll)
+ (void)reStoreToSystemNavigationBar; //change the navigationBar to system style
#import "MXNavigationBarManager.h"
static const CGFloat kNavigationBarHeight = 64.0f;
static const CGFloat kDefaultFullOffset = 200.0f;
static const float kMaxAlphaValue = 0.995f;
static const float kMinAlphaValue = 0.0f;
static const float kDefaultAnimationTime = 0.35f;
#define SCREEN_RECT [UIScreen mainScreen].bounds
#define BACKGROUNDVIEW_FRAME CGRectMake(0, -20, CGRectGetWidth(SCREEN_RECT), kNavigationBarHeight)
@interface MXNavigationBarManager ()
@property (nonatomic, strong) UINavigationBar *selfNavigationBar;
@property (nonatomic, strong) UINavigationController *selfNavigationController;
@property (nonatomic, strong) UIImage *saveImage;
@property (nonatomic, strong) UIColor *saveColor;
@property (nonatomic, strong) UIColor *saveTintColor;
@property (nonatomic, strong) NSDictionary *saveTitleAttribute;
@property (nonatomic, assign) UIStatusBarStyle saveBarStyle;
@property (nonatomic, assign) BOOL setFull;
@property (nonatomic, assign) BOOL setZero;
@property (nonatomic, assign) BOOL setChange;
@end
@implementation MXNavigationBarManager
#pragma mark - property set
+ (void)setBarColor:(UIColor *)color {
[self sharedManager].barColor = color;
}
+ (void)setTintColor:(UIColor *)color {
[self sharedManager].tintColor = color;
[self sharedManager].selfNavigationBar.tintColor = color;
[self setTitleColorWithColor:color];
}
+ (void)setBackgroundImage:(UIImage *)image {
[[self sharedManager].selfNavigationBar setBackgroundImage:image
forBarMetrics:UIBarMetricsDefault];
}
+ (void)setStatusBarStyle:(UIStatusBarStyle)style {
[self sharedManager].statusBarStyle = style;
[[UIApplication sharedApplication] setStatusBarStyle:style];
}
+ (void)setZeroAlphaOffset:(float)offset {
[self sharedManager].zeroAlphaOffset = offset;
}
+ (void)setFullAlphaOffset:(float)offset {
[self sharedManager].fullAlphaOffset = offset;
}
+ (void)setMinAlphaValue:(float)value {
value = value < kMinAlphaValue ? kMinAlphaValue : value;
[self sharedManager].minAlphaValue = value;
}
+ (void)setMaxAlphaValue:(float)value {
value = value > kMaxAlphaValue ? kMaxAlphaValue : value;
[self sharedManager].maxAlphaValue = value;
}
+ (void)setFullAlphaTintColor:(UIColor *)color {
[self sharedManager].fullAlphaTintColor = color;
}
+ (void)setFullAlphaBarStyle:(UIStatusBarStyle)style {
[self sharedManager].fullAlphaBarStyle = style;
}
+ (void)setAllChange:(BOOL)allChange {
[self sharedManager].allChange = allChange;
}
+ (void)setReversal:(BOOL)reversal {
[self sharedManager].reversal = reversal;
}
+ (void)setContinues:(BOOL)continues {
[self sharedManager].continues = continues;
}
+ (void)reStoreToSystemNavigationBar {
[[self sharedManager].selfNavigationController setValue:[UINavigationBar new] forKey:@"navigationBar"];
}
#pragma mark - Public Method
+ (void)managerWithController:(UIViewController *)viewController {
UINavigationBar *navigationBar = viewController.navigationController.navigationBar;
[self sharedManager].selfNavigationController = viewController.navigationController;
[self sharedManager].selfNavigationBar = navigationBar;
[navigationBar setBackgroundImage:[UIImage new] forBarMetrics:UIBarMetricsDefault];
[navigationBar setShadowImage:[UIImage new]];
}
+ (void)changeAlphaWithCurrentOffset:(CGFloat)currentOffset {
MXNavigationBarManager *manager = [self sharedManager];
float currentAlpha = [self curretAlphaForOffset:currentOffset];
if (![manager.barColor isEqual:[UIColor clearColor]]) {
if (!manager.continues) {
if (currentAlpha == manager.minAlphaValue) {
[self setNavigationBarColorWithAlpha:manager.minAlphaValue];
} else if (currentAlpha == manager.maxAlphaValue) {
[UIView animateWithDuration:kDefaultAnimationTime animations:^{
[self setNavigationBarColorWithAlpha:manager.maxAlphaValue];
}];
manager.setChange = YES;
} else {
if (manager.setChange) {
[UIView animateWithDuration:kDefaultAnimationTime animations:^{
[self setNavigationBarColorWithAlpha:manager.minAlphaValue];
}];
manager.setChange = NO;
}
}
} else {
[self setNavigationBarColorWithAlpha:currentAlpha];
}
}
if (manager.allChange) [self changeTintColorWithOffset:currentAlpha];
}
#pragma mark - calculation
+ (float)curretAlphaForOffset:(CGFloat)offset {
MXNavigationBarManager *manager = [self sharedManager];
float currentAlpha = (offset - manager.zeroAlphaOffset) / (float)(manager.fullAlphaOffset - manager.zeroAlphaOffset);
currentAlpha = currentAlpha < manager.minAlphaValue ? manager.minAlphaValue : (currentAlpha > manager.maxAlphaValue ? manager.maxAlphaValue : currentAlpha);
currentAlpha = manager.reversal ? manager.maxAlphaValue + manager.minAlphaValue - currentAlpha : currentAlpha;
return currentAlpha;
}
+ (void)changeTintColorWithOffset:(float)currentAlpha {
MXNavigationBarManager *manager = [self sharedManager];
if (currentAlpha >= manager.maxAlphaValue && manager.fullAlphaTintColor != nil) {
if (manager.setFull) {
manager.setFull = NO;
manager.setZero = YES;
} else {
if (manager.reversal) {
manager.setFull = YES;
}
return;
}
manager.selfNavigationBar.tintColor = manager.fullAlphaTintColor;
[self setTitleColorWithColor:manager.fullAlphaTintColor];
[self setUIStatusBarStyle:manager.fullAlphaBarStyle];
} else if (manager.tintColor != nil) {
if (manager.setZero) {
manager.setZero = NO;
manager.setFull = YES;
} else {
return;
}
manager.selfNavigationBar.tintColor = manager.tintColor;
[self setTitleColorWithColor:manager.tintColor];
[self setUIStatusBarStyle:manager.statusBarStyle];
}
}
#pragma mark - private method
+ (MXNavigationBarManager *)sharedManager {
static MXNavigationBarManager *manager;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
manager = [[MXNavigationBarManager alloc] init];
[self initBaseData:manager];
});
return manager;
}
+ (void)initBaseData:(MXNavigationBarManager *)manager {
manager.maxAlphaValue = kMaxAlphaValue;
manager.minAlphaValue = kMinAlphaValue;
manager.fullAlphaOffset = kDefaultFullOffset;
manager.zeroAlphaOffset = -kNavigationBarHeight;
manager.setZero = YES;
manager.setFull = YES;
manager.allChange = YES;
manager.continues = YES;
}
+ (void)setTitleColorWithColor:(UIColor *)color {
NSMutableDictionary *textAttr = [NSMutableDictionary dictionaryWithDictionary:[self sharedManager].selfNavigationBar.titleTextAttributes];
[textAttr setObject:color forKey:NSForegroundColorAttributeName];
[self sharedManager].selfNavigationBar.titleTextAttributes = textAttr;
}
+ (void)setNavigationBarColorWithAlpha:(float)alpha {
MXNavigationBarManager *manager = [self sharedManager];
NSLog(@"alpha = %f", alpha);
[self setBackgroundImage:[self imageWithColor:[manager.barColor colorWithAlphaComponent:alpha]]];
}
+ (void)setUIStatusBarStyle:(UIStatusBarStyle)style {
[[UIApplication sharedApplication] setStatusBarStyle:style];
}
+ (UIImage *)imageWithColor:(UIColor *)color {
CGRect rect = CGRectMake(0, 0, 1, 1);
UIGraphicsBeginImageContext(rect.size);
CGContextRef context = UIGraphicsGetCurrentContext();
[color setFill];
CGContextFillRect(context, rect);
UIImage *imgae = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return imgae;
}