iOS开发小技巧总结

1.设置导航栏标题颜色

UIColor *whiteColor = [UIColor redColor];
    NSDictionary *dic = [NSDictionary dictionaryWithObject:whiteColor forKey:NSForegroundColorAttributeName];
    [self.navigationController.navigationBar setTitleTextAttributes:dic];

2.设置view半透明，subView不跟着变--通过设置背景色

UIView * backView = [[UIView alloc]initWithFrame:self.view.frame];
    backView.backgroundColor = [[UIColor blackColor] colorWithAlphaComponent:0.5];
    
//    backView.alpha = 0.3;//错误做法
    [self.view addSubview:backView];
    
    UIButton * button = [[UIButton alloc]init];
    button.backgroundColor = [UIColor redColor];
    button.frame = CGRectMake(200, 200, 200, 200);
    button.center = backView.center;
    [backView addSubview:button];

3.设置VIew的部分圆角

CGRect rect = button.bounds;
    CGSize radio = CGSizeMake(50, 50);//圆角尺寸
    UIRectCorner corner = UIRectCornerTopLeft|UIRectCornerTopRight;//这只圆角位置
    UIBezierPath *path = [UIBezierPath bezierPathWithRoundedRect:rect byRoundingCorners:corner cornerRadii:radio];
    CAShapeLayer *masklayer = [[CAShapeLayer alloc]init];//创建shapelayer
    masklayer.frame = button.bounds;
    masklayer.path = path.CGPath;//设置路径
    button.layer.mask = masklayer;

4.数组快速求和，平均值，最大值，最小值

 NSArray *array = [NSArray arrayWithObjects:@"2.0", @"2.3", @"3.0", @"4.0", @"10", nil];
    CGFloat sum = [[array valueForKeyPath:@"@sum.floatValue"] floatValue];
    CGFloat avg = [[array valueForKeyPath:@"@avg.floatValue"] floatValue];
    CGFloat max =[[array valueForKeyPath:@"@max.floatValue"] floatValue];
    CGFloat min =[[array valueForKeyPath:@"@min.floatValue"] floatValue];
    NSLog(@"%f\n向下取整%f\n向上取整%f\n%f\n%f\n%f",sum,floor(sum),ceil(sum),avg,max,min);

5.navigationBar根据滑动距离的渐变色实现

//第一种
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    CGFloat offsetToShow = 200.0;//滑动多少就完全显示
    CGFloat alpha = 1 - (offsetToShow - scrollView.contentOffset.y) / offsetToShow;
    [[self.navigationController.navigationBar subviews] objectAtIndex:0].alpha = alpha;
}
//第二种
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    CGFloat offsetToShow = 200.0;
    CGFloat alpha = 1 - (offsetToShow - scrollView.contentOffset.y) / offsetToShow;
 
    [self.navigationController.navigationBar setShadowImage:[UIImage new]];
    [self.navigationController.navigationBar setBackgroundImage:[self imageWithColor:[[UIColor orangeColor]colorWithAlphaComponent:alpha]] forBarMetrics:UIBarMetricsDefault];
}
 
//根据颜色生成图片
- (UIImage *)imageWithColor:(UIColor *)color
{
    CGRect rect = CGRectMake(0.0f, 0.0f, 1.0f, 1.0f);
    UIGraphicsBeginImageContext(rect.size);
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextSetFillColorWithColor(context, [color CGColor]);
    CGContextFillRect(context, rect);
    UIImage *theImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
 
    return theImage;
}

4.数组快速求和，平均值，最大值，最小值

 NSArray *array = [NSArray arrayWithObjects:@"2.0", @"2.3", @"3.0", @"4.0", @"10", nil];
    CGFloat sum = [[array valueForKeyPath:@"@sum.floatValue"] floatValue];
    CGFloat avg = [[array valueForKeyPath:@"@avg.floatValue"] floatValue];
    CGFloat max =[[array valueForKeyPath:@"@max.floatValue"] floatValue];
    CGFloat min =[[array valueForKeyPath:@"@min.floatValue"] floatValue];
    NSLog(@"%f\n向下取整%f\n向上取整%f\n%f\n%f\n%f",sum,floor(sum),ceil(sum),avg,max,min);

7.获取webView的高度

CGFloat height = [[self.webView stringByEvaluatingJavaScriptFromString:@"document.body.offsetHeight"] floatValue];

8.图片缓存的清空（包括SD的，可以同时清除session 和 cookie的缓存）

// 清理内存
[[SDImageCache sharedImageCache] clearMemory];
 
// 清理webview 缓存
NSHTTPCookieStorage *storage = [NSHTTPCookieStorage sharedHTTPCookieStorage];
for (NSHTTPCookie *cookie in [storage cookies]) {
    [storage deleteCookie:cookie];
}
 
NSURLSessionConfiguration *config = [NSURLSessionConfiguration defaultSessionConfiguration];
[config.URLCache removeAllCachedResponses];
[[NSURLCache sharedURLCache] removeAllCachedResponses];
 
// 清理硬盘
[[SDImageCache sharedImageCache] clearDiskOnCompletion:^{
    [MBProgressHUD hideAllHUDsForView:self.view animated:YES];
 
    [self.tableView reloadData];
}];

9.UIView 自带动画翻转界面

- (IBAction)changeImages:(id)sender
{
    CGContextRef context = UIGraphicsGetCurrentContext();
 
    [UIView beginAnimations:nil context:context];
    [UIView setAnimationCurve:UIViewAnimationCurveEaseInOut];
    [UIView setAnimationDuration:1.0];
 
    [UIView setAnimationTransition:UIViewAnimationTransitionCurlDown forView:_parentView cache:YES];
    [UIView setAnimationTransition:UIViewAnimationTransitionCurlUp forView:_parentView cache:YES];
    [UIView setAnimationTransition:UIViewAnimationTransitionFlipFromLeft forView:_parentView cache:YES];
    [UIView setAnimationTransition:UIViewAnimationTransitionFlipFromRight forView:_parentView cache:YES];
 
    NSInteger purple = [[_parentView subviews] indexOfObject:self.image1];
    NSInteger maroon = [[_parentView subviews] indexOfObject:self.image2];
 
    [_parentView exchangeSubviewAtIndex:purple withSubviewAtIndex:maroon];
 
    [UIView setAnimationDelegate:self];
    [UIView commitAnimations];
 
 
}

10.工程中查看是否使用 IDFA

打开终端，到工程目录中， 输入：

grep -r advertisingIdentifier .

可以看到那些文件中用到了IDFA，如果用到了就会被显示出来

11.动态计算文本高度

NSDictionary *attribute = @{NSFontAttributeName: [UIFont systemFontOfSize:13]};
CGSize size = [@"相关NSString" boundingRectWithSize:CGSizeMake(100, 0) options: NSStringDrawingTruncatesLastVisibleLine | NSStringDrawingUsesLineFragmentOrigin | NSStringDrawingUsesFontLeading attributes:attribute context:nil].size;

12.关闭/收起键盘方法

1、点击Return按扭时收起键盘
- (BOOL)textFieldShouldReturn:(UITextField *)textField 
{
    return [textField resignFirstResponder]; 
}
2、点击背景View收起键盘
[self.view endEditing:YES];
3、你可以在任何地方加上这句话，可以用来统一收起键盘
[[[UIApplication sharedApplication] keyWindow] endEditing:YES];

13.修改textField的placeholder的字体颜色、大小

//方法1
self.textField.placeholder = @"username is in here!";
[self.textField setValue:[UIColor redColor] forKeyPath:@"_placeholderLabel.textColor"];
[self.textField setValue:[UIFont boldSystemFontOfSize:16] forKeyPath:@"_placeholderLabel.font"];
//方法二（实际项目中使用过）
NSString *string = @"美丽新世界";
    NSMutableAttributedString *attributedString = [[NSMutableAttributedString alloc] initWithString:string];
 
    [attributedString addAttribute:NSForegroundColorAttributeName
                             value:[UIColor redColor]
                             range:NSMakeRange(0, [string length])];
 
    [attributedString addAttribute:NSFontAttributeName
                             value:[UIFont systemFontOfSize:16]
                             range:NSMakeRange(0, [string length])];
 
    self.textField.attributedPlaceholder = attributedString;

14.待发现

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15.待发现

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16.待发现

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ps：第一次写没有什么经验就写一点基础简单的吧，我分享的这些都是经过自己验证过的，大家可以放心使用
参考文章1
参考文章2