iOS开发小技巧(一)

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改变UIImagePickerController的导航条以及title的颜色

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- (void)navigationController:(UINavigationController *)navigationController willShowViewController:(UIViewController *)viewController animated:(BOOL)animated
{
   [UIApplication sharedApplication].statusBarStyle = UIStatusBarStyleLightContent;
    UINavigationBar *bar = [UINavigationBar appearance];
    NSMutableDictionary *titleDictionary = [NSMutableDictionary dictionary];
    titleDictionary[NSForegroundColorAttributeName] = [UIColor whiteColor];
    [bar setTitleTextAttributes:titleDictionary];
    viewController.navigationController.navigationBar.barTintColor = DIF_BASE_COLOR;
    viewController.navigationController.navigationBar.tintColor = [UIColor whiteColor];
}

利用KVC改变TextField的占位符的颜色

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[self.nickNameTextField setValue:[UIColor whiteColor] forKeyPath:@"_placeholderLabel.textColor"];

TextView的字数限制

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#define MaxNumberOfDescriptionChars  150

-(void)textViewEditChanged:(NSNotification *)obj{
    UITextView *textView = (UITextView *)obj.object;
    NSString *toBeString = textView.text;
    NSString *lang = [[UITextInputMode currentInputMode] primaryLanguage]; // 键盘输入模式
    if ([lang isEqualToString:@"zh-Hans"]) { // 简体中文输入，包括简体拼音，健体五笔，简体手写
        UITextRange *selectedRange = [textView markedTextRange];
        //获取高亮部分
        UITextPosition *position = [textView positionFromPosition:selectedRange.start offset:0];
        // 没有高亮选择的字，则对已输入的文字进行字数统计和限制
        if (!position) {
            if (toBeString.length > MaxNumberOfDescriptionChars) {
                textView.text = [toBeString substringToIndex:MaxNumberOfDescriptionChars];
            }
        }
        // 有高亮选择的字符串，则暂不对文字进行统计和限制
        else{
        }
    }
    // 中文输入法以外的直接对其统计限制即可，不考虑其他语种情况
    else{
        if (toBeString.length > MaxNumberOfDescriptionChars) {
            
            textView.text = [toBeString substringToIndex:MaxNumberOfDescriptionChars];
        }
    }
}



- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text{
    NSString *new = [textView.text stringByReplacingCharactersInRange:range withString:text];
    self.numLabel.text = [NSString stringWithFormat:@"%zd字",(MaxNumberOfDescriptionChars - new.length)];
    if(new.length > MaxNumberOfDescriptionChars){
         self.numLabel.text = [NSString stringWithFormat:@"%zd字",0];
        if (![text isEqualToString:@""]) {
            return NO;
        }
    }
    return YES;
}

判断字符串或者集合类型是否为空

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+ (BOOL)isEmpty:(id )obj
{
    if ([obj isKindOfClass:[NSString class]]) {
        if(obj == nil || [obj class] == [NSNull null] || [obj isEqualToString:@""] || [obj isEqualToString:@"(null)"] || [obj isEqualToString:@"NULL"] || [obj isEqualToString:@"<null>"] || [obj isEqualToString:@"null"])
        {
            return YES;
        }
        return NO;
    }
    if (obj == nil || (NSNull *)obj == [NSNull null] || ([obj respondsToSelector:@selector(length)] && [obj length] == 0) || ([obj respondsToSelector:@selector(count)] && [obj count] == 0)){
        return YES;
    }
    return NO;
}

给UIResponder添加indexPath属性

列如在cell中有button imageview 可以利用该属性找到cell中改该视图

objective - C

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@interface UIResponder (Externtion)

@property (nonatomic, strong) NSIndexPath *indexPath;

@end
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- (void)setIndexPath:(NSIndexPath *)indexPath
{
    objc_setAssociatedObject(self, @selector(indexPath), indexPath, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}


- (NSIndexPath *)indexPath{
    return objc_getAssociatedObject(self, @selector(indexPath));
}

swift

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extension UIResponder{
    
   private struct AssociatedKey {
    static var AssociatedName = "AssociatedName"
    }
    
    
    public var indexPath: NSIndexPath?{
        get{
           return objc_getAssociatedObject(self, &AssociatedKey.AssociatedName) as? NSIndexPath
        }
        
        set{
            if let newValue = newValue {
                objc_setAssociatedObject(self, &AssociatedKey.AssociatedName, newValue as NSIndexPath , .OBJC_ASSOCIATION_RETAIN_NONATOMIC)
            }
        }
    }
}

UIRefreshControl

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let refresh = UIRefreshControl.init()
        refresh.tintColor = UIColor.red
        refresh.attributedTitle = NSAttributedString.init(string: "正在加载")
        refresh.addTarget(self, action: #selector(ViewController.refreshTabeleView(sender:)), for: UIControlEvents.valueChanged)
        
        
        tableView.refreshControl = refresh
        tableView.addSubview(refresh)
        tableView.reloadData()

将HTML字符串转化为NSAttributedString富文本字符串

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- (NSAttributedString *)attributedStringWithHTMLString:(NSString *)htmlString
{
    NSDictionary *options = @{ NSDocumentTypeDocumentAttribute : NSHTMLTextDocumentType,
                               NSCharacterEncodingDocumentAttribute :@(NSUTF8StringEncoding) };
   
    NSData *data = [htmlString dataUsingEncoding:NSUTF8StringEncoding];
   
    return [[NSAttributedString alloc] initWithData:data options:options documentAttributes:nil error:nil];
}

CABasicAnimation（CAKeyframeAnimation）key path 取值

keyPath可以使用的key

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- define angle2Radian(angle) ((angle)/180.0*M_PI)

transform.rotation.x 围绕x轴翻转 参数：角度 angle2Radian(4)

transform.rotation.y 围绕y轴翻转 参数：同上

transform.rotation.z 围绕z轴翻转 参数：同上

transform.rotation 默认围绕z轴

transform.scale.x x方向缩放 参数：缩放比例 1.5

transform.scale.y y方向缩放 参数：同上

transform.scale.z z方向缩放 参数：同上

transform.scale 所有方向缩放 参数：同上

transform.translation.x x方向移动 参数：x轴上的坐标 100

transform.translation.y x方向移动 参数：y轴上的坐标

transform.translation.z x方向移动 参数：z轴上的坐标

transform.translation 移动 参数：移动到的点 （100，100）

opacity 透明度 参数：透明度 0.5

backgroundColor 背景颜色 参数：颜色 (id)[[UIColor redColor] CGColor]

cornerRadius 圆角 参数：圆角半径 5

borderWidth 边框宽度 参数：边框宽度 5

bounds 大小 参数：CGRect

contents 内容 参数：CGImage

contentsRect 可视内容 参数：CGRect 值是0～1之间的小数

hidden 是否隐藏

position

shadowColor

shadowOffset

shadowOpacity

shadowRadius

隐藏导航条和tabBar的直线

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UINavigationBar *bar = [UINavigationBar appearance];
bar.shadowImage = [UIImage new];
[bar setBackgroundImage:[UIImage new] forBarMetrics:UIBarMetricsDefault];
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UITabBar *tabBar = [UITabBar appearance];
tabBar.shadowImage = [UIImage new];
tabBar.backgroundImage = [UIImage new];

全屏手势返回

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UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc] initWithTarget:self.interactivePopGestureRecognizer.delegate action:@selector(handleNavigationTransition:)];
pan.delegate = self;
[self.view addGestureRecognizer:pan];
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- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch
{
    return self.childViewControllers.count > 1;
}

UITextView的placeholder

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- (void)textViewDidBeginEditing:(UITextView *)textView {
    [self resetTextViewPlaceholderWithText:textView];
}

- (void)textViewDidEndEditing:(UITextView *)textView {
    [self resetTextViewPlaceholderWithText:textView];
}

- (void)resetTextViewPlaceholderWithText:(UITextView *)textView
{
    if ([textView.text isEqualToString:@"要显示的placeholder"]) {
        textView.text = @"";
        textView.textColor = [UIColor blackColor];
        return;
    }
    if (textView.text.length < 1) {
        textView.text = @"要显示的placeholder";
        textView.textColor = [UIColor colorWithRed:0.87 green:0.87 blue:0.87 alpha:1.00];
        return;
    }
}

让应用支持摇一摇

  • 开启摇一摇权限
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[UIApplication sharedApplication].applicationSupportsShakeToEdit = YES;
  • 让view/viewcontroller成为第一响应者
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#pragma mark - UIResponder
- (BOOL)canBecomeFirstResponder {
	return YES;
}
  • 实现方发
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#pragma mark - 摇动
/**
 *  摇动开始
 */
- (void)motionBegan:(UIEventSubtype)motion withEvent:(UIEvent *)event {
    if (motion == UIEventSubtypeMotionShake) {
    // do some thing
    }
}

/**
 *  摇动结束
 */
- (void)motionEnded:(UIEventSubtype)motion withEvent:(UIEvent *)event {
}

/**
 *  摇动取消
 */
- (void)motionCancelled:(UIEventSubtype)motion withEvent:(UIEvent *)event {
}

HeaderView随tableview一起滑动

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- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    if (scrollView == self.tableView) {
        
        CGFloat headerHeight = DIF_SCREEN_HEIGHT / 3;
        if (scrollView.contentOffset.y <= headerHeight && scrollView.contentOffset.y >= 0) {
            scrollView.contentInset = UIEdgeInsetsMake(-scrollView.contentOffset.y, 0, 0, 0);
        }else if (scrollView.contentOffset.y >= headerHeight){
            scrollView.contentInset = UIEdgeInsetsMake(-headerHeight, 0, 0, 0);
        }
    }
}