本文将带你了解IOS开发入门ios之导航渐变---／导航透明，希望本文对大家学IOS有所帮助。

ios之导航渐变---/导航透明。

//   CZNavTableViewController.h

//   导航栏渐变透明效果

#import

@interface   CZNavTableViewController : UITableViewController

@end

================

//   CZNavTableViewController.m

//   导航栏渐变透明效果

//

#import   "CZNavTableViewController.h"

#import "UINavigationBar+alpha.h"

@interface   CZNavTableViewController   ()

@end

@implementation   CZNavTableViewController

- (void)viewDidLoad   {

[super viewDidLoad];

//

//   [self.navigationController.navigationBar setBackgroundColor:[UIColor   redColor]];

//

//   [self.navigationController.navigationBar setBarTintColor:[UIColor   redColor]];

// [self.navigationController.navigationBar   setTintColor:[UIColor redColor]];

//   [self.navigationController.navigationBar setBackgroundImage:[UIImage   imageNamed:@"NavBar64"] forBarMetrics:UIBarMetricsDefault];

}

-(void)scrollViewDidScroll:(UIScrollView   *)scrollView

{

//当前的y值

CGFloat   OffsetY = scrollView.contentOffset.y;

UIColor *color =   [UIColor redColor];

CGFloat alpha = (30 + 64 -   OffsetY)/64;

if (OffsetY > 30)   {

[self.navigationController.navigationBar   alphaNavigationBarView:[color   colorWithAlphaComponent:alpha]];

}else

{

[self.navigationController.navigationBar   alphaNavigationBarView:[color   colorWithAlphaComponent:1]];

}

}

#pragma   mark - Table view data source

- (NSInteger)numberOfSectionsInTableView:(UITableView   *)tableView {

#warning Incomplete implementation, return   the number of sections

return   0;

}

- (NSInteger)tableView:(UITableView   *)tableView numberOfRowsInSection:(NSInteger)section   {

#warning Incomplete implementation, return the number of   rows

return   0;

}

=================

#import

@interface   UINavigationBar (alpha)

//动态添加的UIview 添加到UINavigationBar   上

@property (nonatomic , strong)UIView   *alphaView;

- (void)alphaNavigationBarView:(UIColor   *)color;

@end

===========

#import   "UINavigationBar+alpha.h"

#import

@implementation   UINavigationBar (alpha)

static char   alView;

-(UIView *)alphaView

{

return   objc_getAssociatedObject(self,   &alView);

}

-(void)setAlphaView:(UIView   *)alphaView

{

objc_setAssociatedObject(self,   &alView, alphaView,   OBJC_ASSOCIATION_RETAIN_NONATOMIC);

}

//通过这个方法去改变颜色和透明度

-(void)alphaNavigationBarView:(UIColor   *)color

{

if (!self.alphaView)   {

//设置一张图片,如果不设置,颜色不纯

[self   setBackgroundImage:[UIImage new]   forBarMetrics:UIBarMetricsDefault];

//创建

self.alphaView   = [[UIView alloc]initWithFrame:CGRectMake(0, -20,[UIScreen   mainScreen].bounds.size.width , 64)];

//添加到navigationbar

[self   insertSubview:self.alphaView   atIndex:0];

}

[self.alphaView   setBackgroundColor:color];

}

@end

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