人过留名，雁过留声，当自己老了回首今朝，假如有这么个记录着自己成长的简书，应该也是别有一番感受吧！记录自己成长的点点滴滴，每天进步一点点，终会达到自己梦想的彼岸！

1、设置UITextField的placeholder字体的颜色和字号

textField.placeholder = @"请输入用户名";  
[textField setValue:[UIColor redColor] forKeyPath:@"_placeholderLabel.textColor"];  
[textField setValue:[UIFont boldSystemFontOfSize:16] forKeyPath:@"_placeholderLabel.font"];

// <#注释#>

2、创建按钮添加拖动和点击事件

//添加点击事件
[btn addTarget:self action:@selector(btnClick:) forControlEvents:UIControlEventTouchUpInside];
//添加拖动事件
[btn addTarget:self action:@selector(dragMoving:withEvent:)forControlEvents: UIControlEventTouchDragInside];
//添加拖动结束时的事件
[btn addTarget:self action:@selector(dragEnded:withEvent:)forControlEvents: UIControlEventTouchUpInside];

/**
  *事件
  */
//拖动过程中
- (void)dragMoving:(UIControl *)c withEvent:ev
{
    CGPoint point = [[[ev allTouches] anyObject] locationInView:self.view];   
    point.x = MIN(MAX(point.x, btn.width * 0.5 + 10) , self.view.width - btn.width * 0.5 - 10);//范围
    point.y = MIN(MAX(point.y, 100), self.view.height - btn.height * 0.5 - 10);//范围
    c.center = point;
    _isClick = NO;
}
//拖动结束
- (void)dragEnded:(UIControl *)c withEvent:ev
{
    XDLog(@"dragEnded....");   
    CGPoint point = [[[ev allTouches] anyObject] locationInView:self.view];
    point.x = MIN(MAX(point.x, btn.width * 0.5 + 10), self.view.width - btn.width * 0.5 - 10);//范围
    point.y = MIN(MAX(point.y, 100) , self.view.height - btn.height * 0.5 - 10);//范围
    c.center = point;
    [UIView animateWithDuration:0.2 animations:^{
        c.centerX = c.centerX < self.view.width - c.centerX ? 30 : self.view.width - 30;
    }];
    _isClick = YES;
}
//点击事件
- (void)btnClick:(UIButton *)btn
{
    if (_isClick) {
        //点击方法
    }
}

3、判断是否同一日

- (BOOL)isSameDay:(NSDate*)date1 date2:(NSDate*)date2
{
    NSCalendar* calendar = [NSCalendar currentCalendar];
    
    unsigned unitFlags = NSCalendarUnitYear | NSCalendarUnitMonth |  NSCalendarUnitDay;
    NSDateComponents* comp1 = [calendar components:unitFlags fromDate:date1];
    NSDateComponents* comp2 = [calendar components:unitFlags fromDate:date2];
        
    return [comp1 day]   == [comp2 day] &&
    [comp1 month] == [comp2 month] &&
    [comp1 year]  == [comp2 year];
}

4、禁止横屏

-(UIInterfaceOrientationMask)application:(UIApplication *)application supportedInterfaceOrientationsForWindow:(UIWindow *)window
{
    return UIInterfaceOrientationMaskPortrait;
}

5、电池状态栏改变颜色

 [self.navigationController.navigationBar setBarStyle:UIBarStyleBlack];

默认的黑色（UIStatusBarStyleDefault）
白色（UIStatusBarStyleLightContent）

- (UIStatusBarStyle)preferredStatusBarStyle
{
    return UIStatusBarStyleLightContent;
}

6、UITableView的Group样式下顶部空白处理

UIView *view = [[UIView alloc] initWithFrame:CGRectZero];
self.tableView.tableHeaderView = view;

#pragma mark - 处理导航栏下1px横线
_imageView = [self findHairlineImageViewUnder:self.navigationController.navigationBar];

- (UIImageView *)findHairlineImageViewUnder:(UIView *)view {
    if ([view isKindOfClass:UIImageView.class] && view.bounds.size.height <= 1.0) {
        return (UIImageView *)view;
    }
    for (UIView *subview in view.subviews) {
        UIImageView *imageView = [self findHairlineImageViewUnder:subview];
        if (imageView) {
            return imageView;
        }
    }
    return nil;
}

//UITableView点击一下就出现灰色但是立马消失掉。

//点击那一刻可以指示出点击了哪一行，灰色停留一秒钟消失掉。

//1.设置cell点击时候为灰色

cell.selectionStyle = UITableViewCellSelectionStyleGray;  

//2.在tableView代理方法didSelectedRow方法这样写

- (void)tableView：(UITableView *)tableView didSelecteRowAtIndexPath:(NSIndexPath *)indexPath{

      [ tableView deselectRowAtIndexPath:indexPath animated:YES];//直接取消选中这一行

}

7、对图片尺寸进行压缩

-(UIImage*)imageWithImage:(UIImage*)image scaledToSize:(CGSize)newSize
{
    // Create a graphics image context
    UIGraphicsBeginImageContext(newSize);
    
    // Tell the old image to draw in this new context, with the desired
    // new size
    [image drawInRect:CGRectMake(0,0,newSize.width,newSize.height)];
    
    // Get the new image from the context
    UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();
    
    // End the context
    UIGraphicsEndImageContext();
    
    // Return the new image.
    return newImage;
}

8、虚线图片

- (UIImage *)imageWithSize:(CGSize)size borderColor:(UIColor *)color borderWidth:(CGFloat)borderWidth
{
    UIGraphicsBeginImageContextWithOptions(size, NO, 0.0);
    [[UIColor clearColor] set];
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextBeginPath(context);
    CGContextSetLineWidth(context, borderWidth);
    CGContextSetStrokeColorWithColor(context, color.CGColor);
    CGFloat lengths[] = { 3, 1 };
    CGContextSetLineDash(context, 0, lengths, 1);
    CGContextMoveToPoint(context, 0.0, 0.0);
    CGContextAddLineToPoint(context, size.width, 0.0);
    CGContextAddLineToPoint(context, size.width, size.height);
    CGContextAddLineToPoint(context, 0, size.height);
    CGContextAddLineToPoint(context, 0.0, 0.0);
    CGContextStrokePath(context);
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return image;
}

9、禁止当前页面的返回手势

- (void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];
    // 禁用返回手势
    if ([self.navigationController respondsToSelector:@selector(interactivePopGestureRecognizer)]) {
        self.navigationController.interactivePopGestureRecognizer.enabled = NO;
    }
}

- (void)viewWillDisappear:(BOOL)animated
{
    [super viewWillDisappear:animated];
    // 开启返回手势
    if ([self.navigationController respondsToSelector:@selector(interactivePopGestureRecognizer)]) {
        self.navigationController.interactivePopGestureRecognizer.enabled = YES;
    }
}

10、在 button 加载网络图片

// 1、单独加载网络图片 可以用SDWebImage 下的 "UIButton+WebCache.h"
 [btn sd_setImageWithURL:[NSURL URLWithString:model.imgurl] forState:UIControlStateNormal];

// 2、加载网络图片和文字时·需要注意图片的大小
/**
 *  异步加载图片
 */
   [[SDImageCache sharedImageCache] storeImage:btn.imageView.image forKey:urlStr toDisk:NO];
   [[SDWebImageManager sharedManager] downloadImageWithURL:[NSURL URLWithString:urlStr] options:0 progress:nil completed:^(UIImage *image, NSError *error, SDImageCacheType cacheType, BOOL finished, NSURL *imageURL) {
        // 主线程刷新UI
      dispatch_async(dispatch_get_main_queue(), ^{
            CGSize imagesize;  //需要图片的大小
            UIImage *smallImage = [self imageWithImage:image scaledToSize:imagesize];//裁剪
            [btn setImage:smallImage forState:UIControlStateNormal];
            [btn setTitle:name forState:UIControlStateNormal];
            btn.contentHorizontalAlignment = UIControlContentHorizontalAlignmentLeft;
            btn.titleEdgeInsets = UIEdgeInsetsMake(0, 10, 0, 0);
        });
       
    }];

11、button 按钮图片和文字(图片左·文字右，文字隔图片10px)

   //当图片过大时·文字可能显示不出来·所以要把图片压缩成button一样的高度·就可以显示出来
   [btn setImage:image forState:UIControlStateNormal];
   [btn setTitle:name forState:UIControlStateNormal];
   btn.contentHorizontalAlignment = UIControlContentHorizontalAlignmentLeft;
   btn.titleEdgeInsets = UIEdgeInsetsMake(0, 10, 0, 0);

    //button 折行显示设置
    /*
     NSLineBreakByWordWrapping = 0,         // Wrap at word boundaries, default
     NSLineBreakByCharWrapping,     // Wrap at character boundaries
     NSLineBreakByClipping,     // Simply clip 裁剪从前面到后面显示多余的直接裁剪掉
     
     文字过长 button宽度不够时: 省略号显示位置...
     NSLineBreakByTruncatingHead,   // Truncate at head of line: "...wxyz" 前面显示
     NSLineBreakByTruncatingTail,   // Truncate at tail of line: "abcd..." 后面显示
     NSLineBreakByTruncatingMiddle  // Truncate middle of line:  "ab...yz" 中间显示省略号
     */
    button.titleLabel.lineBreakMode = NSLineBreakByWordWrapping;
    // you probably want to center it
    button.titleLabel.textAlignment = NSTextAlignmentCenter; // if you want to
    button.layer.borderColor = [UIColor blackColor].CGColor;
    button.layer.borderWidth = 1.0;
    
    // underline Terms and condidtions
    NSMutableAttributedString* tncString = [[NSMutableAttributedString alloc] initWithString:@"View Terms and Conditions"];
    
    //设置下划线...
    /*
     NSUnderlineStyleNone                                    = 0x00, 无下划线
     NSUnderlineStyleSingle                                  = 0x01, 单行下划线
     NSUnderlineStyleThick NS_ENUM_AVAILABLE(10_0, 7_0)      = 0x02, 粗的下划线
     NSUnderlineStyleDouble NS_ENUM_AVAILABLE(10_0, 7_0)     = 0x09, 双下划线
     */
    [tncString addAttribute:NSUnderlineStyleAttributeName
                      value:@(NSUnderlineStyleSingle)
                      range:(NSRange){0,[tncString length]}];
    //此时如果设置字体颜色要这样
    [tncString addAttribute:NSForegroundColorAttributeName value:[UIColor blueColor]  range:NSMakeRange(0,[tncString length])];
    
    //设置下划线颜色...
    [tncString addAttribute:NSUnderlineColorAttributeName value:[UIColor redColor] range:(NSRange){0,[tncString length]}];
    [button setAttributedTitle:tncString forState:UIControlStateNormal];

12、在xib(storyboard)中使用 UIScrollView, 默认是勾选了autolayout选项的，在autolayout下,iOS计算UIScrollView的contentsize的机制

• iOS7中，需在viewDidLayoutSubviews中设置scrollView.contentSize属性

-(void)viewDidLayoutSubviews
{
    self.scrollView.contentSize = CGSizeMake(xx,xx);
}

• iOS8及以上，只需要在viewDidAppear方法中设置就好了

-(void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];
    self.scrollView.contentSize = CGSizeMake(xx,xx);
}

所以，如果要最低支持iOS7系统，只需在viewDidLayoutSubviews中设置contentSize属性即可。

13、刷新框架的适配iOS11

• 如果你使用了MJRefresh等刷新，并且你还隐藏了导航

if (@available(iOS 11.0, *)) {
        self.tableview.contentInsetAdjustmentBehavior = UIApplicationBackgroundFetchIntervalNever;
    } else {
        self.automaticallyAdjustsScrollViewInsets = false;
    }

//代码适配iOS11

#define naviBarH ([[UIApplication sharedApplication] statusBarFrame].size.height + 44)
#define tabBarH ([[UIApplication sharedApplication] statusBarFrame].size.height>20?83:49)
#define AboveIOS9  ([[[UIDevice currentDevice] systemVersion] floatValue] >= 9.0)
// iPhone X 尺寸 375*812
#define XY_iPhoneX (IS_IPHONE && XY_ScreenWidth == 375.f && XY_ScreenHeight == 812.f)
#define IS_IPHONE (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone)
#define SafeAreaBottomHeight (kWJScreenHeight == 812.0 ? 34 : 0)

//iOS11 刷新单个cell或者刷新一组cell 的时候需要用到，不然会移动
 _tableView.estimatedRowHeight = 0;
 _tableView.estimatedSectionHeaderHeight = 0;
 _tableView.estimatedSectionFooterHeight = 0;

//代码适配安全区域
- (void)viewSafeAreaInsetsDidChange {
    [super viewSafeAreaInsetsDidChange];
     
    NSLog(@"viewSafeAreaInsetsDidChange-%@",NSStringFromUIEdgeInsets(self.view.safeAreaInsets));
     
    [self updateOrientation];
}
- (void)updateOrientation {
    if (@available(iOS 11.0, *)) {
        CGRect frame = self.customerView.frame;
        frame.origin.x = self.view.safeAreaInsets.left;
        frame.size.width = self.view.frame.size.width - self.view.safeAreaInsets.left - self.view.safeAreaInsets.right;
        frame.size.height = self.view.frame.size.height - self.view.safeAreaInsets.bottom;
        self.customerView.frame = frame;
    } else {
        // Fallback on earlier versions
    }
}

14、xcode打印的位置，方法，行数

#ifdef DEBUG
    #if TARGET_IPHONE_SIMULATOR//模拟器

#define NSLog(...) NSLog(@"%s 第%d行 \n %@\n\n",__func__,__LINE__,[NSString stringWithFormat:__VA_ARGS__])

    #elif TARGET_OS_IPHONE//真机

        #define NSLog(...) NSLog(@"%s 第%d行 \n %@\n\n",__func__,__LINE__,[NSString stringWithFormat:__VA_ARGS__])

        //#define NSLog(...) fprintf(stderr,"[%s-%d行] %s\n",[[[NSString stringWithUTF8String:__FILE__] lastPathComponent] UTF8String], __LINE__, [[NSString stringWithFormat:@"%@", ##__VA_ARGS__] UTF8String]);

    #endif

#else

    //正式发布
    #ifdef zhengShiFaBu

        #define NSLog(...)

    #else

        #define NSLog(...) NSLog(__VA_ARGS__)

    #endif

#endif

15、弱引用、强引用

#ifndef weakify
#if DEBUG
#if __has_feature(objc_arc)
#define weakify(object) autoreleasepool{} __weak __typeof__(object) weak##_##object = object;
#else
#define weakify(object) autoreleasepool{} __block __typeof__(object) block##_##object = object;
#endif
#else
#if __has_feature(objc_arc)
#define weakify(object) try{} @finally{} {} __weak __typeof__(object) weak##_##object = object;
#else
#define weakify(object) try{} @finally{} {} __block __typeof__(object) block##_##object = object;
#endif
#endif
#endif

#ifndef strongify
#if DEBUG
#if __has_feature(objc_arc)
#define strongify(object) autoreleasepool{} __typeof__(object) object = weak##_##object;
#else
#define strongify(object) autoreleasepool{} __typeof__(object) object = block##_##object;
#endif
#else
#if __has_feature(objc_arc)
#define strongify(object) try{} @finally{} __typeof__(object) object = weak##_##object;
#else
#define strongify(object) try{} @finally{} __typeof__(object) object = block##_##object;
#endif
#endif
#endif

16、UITableView

• xib 创建cell. 先注册

[self.tableView registerNib:[UINib
                                 nibWithNibName:NSStringFromClass([MyCell class])
                                 bundle:nil]
         forCellReuseIdentifier:ID];

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{

    MyCell * cell = [tableView dequeueReusableCellWithIdentifier:@"ID"];
    

• sb 创建cell. 直接

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    MyCell * cell = [tableView dequeueReusableCellWithIdentifier:@"ID"];

17、根据UITableView点击tableviewCell获取在当前屏幕中的坐标值

CGRect rectInTableView = [tableView rectForRowAtIndexPath:indexPath];   
CGRect rect = [tableView convertRect:rectInTableView toView:[tableView superview]];   

18、UITableView 刷新

//一个section刷新    
NSIndexSet *indexSet=[[NSIndexSet alloc]initWithIndex:1]; //你需要更新的组数   
[tableview reloadSections:indexSet withRowAnimation:UITableViewRowAnimationAutomatic];  //collection 相同  
//一个cell刷新    
NSIndexPath *indexPath=[NSIndexPath indexPathForRow:3 inSection:0];  //你需要更新的组数中的cell  
[tableView reloadRowsAtIndexPaths:[NSArray arrayWithObjects:indexPath,nil] withRowAnimation:UITableViewRowAnimationNone]; //collection 相同

19、UITableViewcell 镶嵌 UITextField 复用的问题

• 因为cell每次滑动过程都是从缓存池中去取·所以需要建一个数据来保存
  在cell里面用blokc把每次改变的值传过去 然后保存起来

//1
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
    if (block) {
        block([textField.text stringByReplacingCharactersInRange:range withString:string]);
    }
    return YES;;
}

//2
        cell. block = ^(NSString *title) {
            [self.dataDic setObject:title forKey:@(indexPath.row)];
        };
        NSArray *arr = [self.dataDic allKeys];
        if ([arr containsObject:@(indexPath.row)]) {
            cell.textField.text = [self.dataDic objectForKey:@(indexPath.row)];
        }else{
            cell.textField.text = nil;
        }

20、手机屏幕一直亮着

[UIApplication sharedApplication].idleTimerDisabled = YES;

21、UILabel的文字里面有特殊字符的时候（数字，空格等）,会自动换行的问题

textLabel.lineBreakMode = NSLineBreakByCharWrapping;

// 文字和图片混合排列
   NSTextAttachment *attach = [[NSTextAttachment alloc] initWithData:nil ofType:nil];
    attach.image = [UIImage imageNamed:@"test"];
    NSMutableAttributedString* attrString = [[NSMutableAttributedString alloc] initWithString:@"文字\uFFFC混合排列"];
    [attrString addAttribute:NSAttachmentAttributeName value:attach range:NSMakeRange(0, attrString.length)];
    
    _labeltest.attributedText = attrString;