iOS大杂烩-常用小知识

打印View所有子视图
po [[self view]recursiveDescription]
layoutSubviews调用的调用时机* 当视图第一次显示的时候会被调用* 当这个视图显示到屏幕上了,点击按钮* 添加子视图也会调用这个方法* 当本视图的大小发生改变的时候是会调用的* 当子视图的frame发生改变的时候是会调用的* 当删除子视图的时候是会调用的
NSString过滤特殊字符

// 定义一个特殊字符的集合
NSCharacterSet *set = [NSCharacterSet characterSetWithCharactersInString:@"@／：；（）¥「」＂、[]{}#%-*+=_\\|~＜＞$€^•'@#$%^&*()_+'\""];// 过滤字符串的特殊字符NSString *newString = [trimString stringByTrimmingCharactersInSet:set];

TransForm属性

//平移按钮
CGAffineTransform transForm = self.buttonView.transform;self.buttonView.transform = CGAffineTransformTranslate(transForm, 10, 0);
//旋转按钮
CGAffineTransform transForm = self.buttonView.transform;self.buttonView.transform = CGAffineTransformRotate(transForm, M_PI_4);
//缩放按钮
self.buttonView.transform = CGAffineTransformScale(transForm, 1.2, 1.2);//初始化复位self.buttonView.transform = CGAffineTransformIdentity;

去掉分割线多余15像素首先在viewDidLoad方法加入以下代码：

 if ([self.tableView respondsToSelector:@selector(setSeparatorInset:)]) {        [self.tableView setSeparatorInset:UIEdgeInsetsZero];    } 
   if ([self.tableView respondsToSelector:@selector(setLayoutMargins:)]) {                [self.tableView setLayoutMargins:UIEdgeInsetsZero];}

计算方法耗时时间间隔

// 获取时间间隔#define TICK  CFAbsoluteTime start = CFAbsoluteTimeGetCurrent();#define TOCK  NSLog(@"Time: %f", CFAbsoluteTimeGetCurrent() - start)

Color颜色宏定义

// 随机颜色
#define RANDOM_COLOR [UIColor colorWithRed:arc4random_uniform(256) / 255.0 green:arc4random_uniform(256) / 255.0 blue:arc4random_uniform(256) / 255.0 alpha:1]// 颜色(RGB)#define RGBCOLOR(r, g, b) [UIColor colorWithRed:(r)/255.0f green:(g)/255.0f blue:(b)/255.0f alpha:1]#define RGBACOLOR(r, g, b, a) [UIColor colorWithRed:(r)/255.0f green:(g)/255.0f blue:(b)/255.0f alpha:(a)]

Alert提示宏定义

#define Alert(_S_, ...) [[[UIAlertView alloc] initWithTitle:@"提示" message:[NSString stringWithFormat:(_S_), ##__VA_ARGS__] delegate:nil cancelButtonTitle:@"确定" otherButtonTitles:nil] show]8，让 iOS 应用直接退出- (void)exitApplication {    AppDelegate *app = [UIApplication sharedApplication].delegate;    UIWindow *window = app.window;    [UIView animateWithDuration:1.0f animations:^{        window.alpha = 0;    } completion:^(BOOL finished) {        exit(0);    }];}

NSArray 快速求总和最大值最小值和平均值

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%f\n%f\n%f",sum,avg,max,min);

检测是否IPad Pro

- (BOOL)isIpadPro

{

UIScreen *Screen = [UIScreen mainScreen];

CGFloat width = Screen.nativeBounds.size.width/Screen.nativeScale;

CGFloat height = Screen.nativeBounds.size.height/Screen.nativeScale;

BOOL isIpad =[[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPad;

BOOL hasIPadProWidth = fabs(width - 1024.f) < DBL_EPSILON;

BOOL hasIPadProHeight = fabs(height - 1366.f) < DBL_EPSILON;

return isIpad && hasIPadProHeight && hasIPadProWidth;

}

修改Tabbar Item的属性

// 修改标题位置

self.tabBarItem.titlePositionAdjustment = UIOffsetMake(0, -10);

// 修改图片位置

self.tabBarItem.imageInsets = UIEdgeInsetsMake(-3, 0, 3, 0);

// 批量修改属性

for (UIBarItem *item in self.tabBarController.tabBar.items) {

[item setTitleTextAttributes:[NSDictionary dictionaryWithObjectsAndKeys:

[UIFont fontWithName:@"Helvetica" size:19.0], NSFontAttributeName, nil]

forState:UIControlStateNormal];

}

// 设置选中和未选中字体颜色

[[UITabBar appearance] setShadowImage:[[UIImage alloc] init]];

//未选中字体颜色

[[UITabBarItem appearance] setTitleTextAttributes:@{NSForegroundColorAttributeName:[UIColor greenColor]} forState:UIControlStateNormal];

//选中字体颜色

[[UITabBarItem appearance] setTitleTextAttributes:@{NSForegroundColorAttributeName:[UIColor cyanColor]} forState:UIControlStateSelected];

NULL - nil - Nil - NSNULL的区别

nil是OC的，空对象，地址指向空（0）的对象。对象的字面零值
Nil是Objective-C类的字面零值
NULL是C的，空地址，地址的数值是0，是个长整数
NSNull用于解决向NSArray和NSDictionary等集合中添加空值的问题

去掉BackBarButtonItem的文字

[[UIBarButtonItem appearance] setBackButtonTitlePositionAdjustment:UIOffsetMake(0, -60)
forBarMetrics:UIBarMetricsDefault];

控件不能交互的一些原因

控件的userInteractionEnabled = NO
透明度小于等于0.01，aplpha
控件被隐藏的时候，hidden = YES
子视图的位置超出了父视图的有效范围，子视图无法交互，设置了

修改UITextField中Placeholder的文字颜色

[text setValue:[UIColor redColor] forKeyPath:@"_placeholderLabel.textColor"];

视图的生命周期

alloc 创建对象，分配空间
init (initWithNibName) 初始化对象，初始化数据
loadView 从nib载入视图，除非你没有使用xib文件创建视图
viewDidLoad 载入完成，可以进行自定义数据以及动态创建其他控件
viewWillAppear视图将出现在屏幕之前，马上这个视图就会被展现在屏幕上了
viewDidAppear 视图已在屏幕上渲染完成
viewWillDisappear 视图将被从屏幕上移除之前执行
viewDidDisappear 视图已经被从屏幕上移除，用户看不到这个视图了
dealloc 视图被销毁，此处需要对你在init和viewDidLoad中创建的对象进行释放.
viewVillUnload－当内存过低，即将释放时调用；
viewDidUnload－当内存过低，释放一些不需要的视图时调用。

判断view是不是指定视图的子视图

BOOL isView =  [textView isDescendantOfView:self.view];

页面强制横屏

//pragma mark - 强制横屏代码

- (BOOL)shouldAutorotate{

//是否支持转屏

return NO;

}

- (UIInterfaceOrientationMask)supportedInterfaceOrientations{

//支持哪些转屏方向

return UIInterfaceOrientationMaskLandscape;

}

- (UIInterfaceOrientation)preferredInterfaceOrientationForPresentation{

return UIInterfaceOrientationLandscapeRight;

}

- (BOOL)prefersStatusBarHidden{

return NO;

}

系统键盘通知消息

UIKeyboardWillShowNotification-将要弹出键盘
UIKeyboardDidShowNotification-显示键盘
UIKeyboardWillHideNotification-将要隐藏键盘
UIKeyboardDidHideNotification-键盘已经隐藏
UIKeyboardWillChangeFrameNotification-键盘将要改变frame
UIKeyboardDidChangeFrameNotification-键盘已经改变frame

关闭navigationController的滑动返回手势

self.navigationController.interactivePopGestureRecognizer.enabled = NO;

设置状态栏为任意的颜色

- (void)setStatusColor

{

UIView *statusBarView = [[UIView alloc] initWithFrame:CGRectMake(0, 0,[UIScreen mainScreen].bounds.size.width, 20)];

statusBarView.backgroundColor = [UIColor orangeColor];

[self.view addSubview:statusBarView];

}

让Xcode的控制台支持LLDB类型的打印

打开终端输入三条命令:

touch ~/.lldbinit

echo display @import UIKit >> ~/.lldbinit

echo target stop-hook add -o \"target stop-hook disable\" >> ~/.lldbinit

下次重新运行项目，然后就不报错了。

Label行间距

-（void）test{

NSMutableAttributedString *attributedString =

[[NSMutableAttributedString alloc] initWithString:self.contentLabel.text];

NSMutableParagraphStyle *paragraphStyle =  [[NSMutableParagraphStyle alloc] init];

[paragraphStyle setLineSpacing:3];

//调整行间距

[attributedString addAttribute:NSParagraphStyleAttributeName

value:paragraphStyle

range:NSMakeRange(0, [self.contentLabel.text length])];

self.contentLabel.attributedText = attributedString;

}

UIImageView填充模式

@"UIViewContentModeScaleToFill",      // 拉伸自适应填满整个视图

@"UIViewContentModeScaleAspectFit",  // 自适应比例大小显示

@"UIViewContentModeScaleAspectFill",  // 原始大小显示

@"UIViewContentModeRedraw",          // 尺寸改变时重绘

@"UIViewContentModeCenter",          // 中间

@"UIViewContentModeTop",              // 顶部

@"UIViewContentModeBottom",          // 底部

@"UIViewContentModeLeft",            // 中间贴左

@"UIViewContentModeRight",            // 中间贴右

@"UIViewContentModeTopLeft",          // 贴左上

@"UIViewContentModeTopRight",        // 贴右上

@"UIViewContentModeBottomLeft",      // 贴左下

@"UIViewContentModeBottomRight",      // 贴右下

获取时间

//获取当地时间
- (NSString *)getCurrentTime {
    NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
    [formatter setDateFormat:@"yyyy-MM-dd"];
    NSString *dateTime = [formatter stringFromDate:[NSDate date]];
    return dateTime;
}
//将字符串转成NSDate类型
- (NSDate *)dateFromString:(NSString *)dateString {
    
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setDateFormat: @"yyyy-MM-dd"];
    NSDate *destDate= [dateFormatter dateFromString:dateString];
    return destDate;
}
//传入今天的时间，返回明天的时间
- (NSString *)GetTomorrowDay:(NSDate *)aDate {
    NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSCalendarIdentifierGregorian];
    NSDateComponents *components = [gregorian components:NSCalendarUnitWeekday | NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay fromDate:aDate];
    [components setDay:([components day]+1)];
    
    NSDate *beginningOfWeek = [gregorian dateFromComponents:components];
    NSDateFormatter *dateday = [[NSDateFormatter alloc] init];
    [dateday setDateFormat:@"yyyy-MM-dd"];
    return [dateday stringFromDate:beginningOfWeek];
}

iOS大杂烩-常用小知识

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