#pragma mark - 顶!d=====( ̄▽ ̄*)b部的导航渐变
- (void)scrollViewDidScroll:(UIScrollView *)scrollView{
NSLog(@"当前的offset %f",scrollView.contentOffset.y);
float currentAlpha = (scrollView.contentOffset.y+TOPSCREENHIGHT)/(float)(52+64);
UIColor *color = TABBARCOLOR;
UIImage *image = [self imageWithColor:[color colorWithAlphaComponent:currentAlpha]];
if (scrollView.contentOffset.y == 0.000) {
image = [self imageWithColor:[color colorWithAlphaComponent:0]];
}
[self.navigationController.navigationBar setBackgroundImage:image forBarMetrics:UIBarMetricsDefault];
[self.navigationController.navigationBar setShadowImage:image];
if (currentAlpha >= 1) {
self.title = @"课程详情";
}else{
self.title = @"";
}
}
- (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;
}
- (UIImage *)imageWithColor:(UIColor *)color andSize:(CGSize)size {
CGRect rect = CGRectMake(0, 0, size.width, size.height);
UIGraphicsBeginImageContext(rect.size);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetFillColorWithColor(context, [color CGColor]);
CGContextFillRect(context, rect);
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
CGContextAddEllipseInRect(context, rect);
UIGraphicsEndImageContext();
return image;
}
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