iOS 知识-常用小技巧大杂烩
1,打印View所有子视图
po [[self view]recursiveDescription]
2,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
3,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];
4,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;
5,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];
}
然后在重写willDisplayCell方法
- (void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell
forRowAtIndexPath:(NSIndexPath *)indexPath{
if ([cell respondsToSelector:@selector(setSeparatorInset:)]) {
[cell setSeparatorInset:UIEdgeInsetsZero];
}
if ([cell respondsToSelector:@selector(setLayoutMargins:)]) {
[cell setLayoutMargins:UIEdgeInsetsZero];
}
}
6,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)
7,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)]
8,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);
}];
}
8,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);
9,修改Label中不同文字颜色
- (void)touchesEnded:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{
[self editStringColor:self.label.text editStr:@"好" color:[UIColor blueColor]];
}
- (void)editStringColor:(NSString *)string editStr:(NSString *)editStr color:(UIColor *)color {
// string为整体字符串, editStr为需要修改的字符串
NSRange range = [string rangeOfString:editStr];
NSMutableAttributedString *attribute = [[NSMutableAttributedString alloc] initWithString:string];
// 设置属性修改字体颜色UIColor与大小UIFont
[attribute addAttributes:@{NSForegroundColorAttributeName:color} range:range];
self.label.attributedText = attribute;
}
10,播放声音
#import<AVFoundation/AVFoundation.h>
// 1.获取音效资源的路径
NSString *path = [[NSBundle mainBundle]pathForResource:@"pour_milk" ofType:@"wav"];
// 2.将路劲转化为url
NSURL *tempUrl = [NSURL fileURLWithPath:path];
// 3.用转化成的url创建一个播放器
NSError *error = nil;
AVAudioPlayer *play = [[AVAudioPlayer alloc]initWithContentsOfURL:tempUrl error:&error];
self.player = play;
// 4.播放
[play play];
11,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;
}
11,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];
12,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
11,去掉BackBarButtonItem的文字
[[UIBarButtonItem appearance] setBackButtonTitlePositionAdjustment:UIOffsetMake(0, -60)
forBarMetrics:UIBarMetricsDefault];
12,控件不能交互的一些原因
1,控件的userInteractionEnabled = NO
2,透明度小于等于0.01,aplpha
3,控件被隐藏的时候,hidden = YES
4,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
12,修改UITextField中Placeholder的文字颜色
[text setValue:[UIColor redColor] forKeyPath:@"_placeholderLabel.textColor"];
}
13,视图的生命周期
1、 alloc 创建对象,分配空间
2、 init (initWithNibName) 初始化对象,初始化数据
3、 loadView 从nib载入视图 ,除非你没有使用xib文件创建视图
4、 viewDidLoad 载入完成,可以进行自定义数据以及动态创建其他控件
5、 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
6、 viewDidAppear 视图已在屏幕上渲染完成
1、viewWillDisappear 视图将被从屏幕上移除之前执行
2、viewDidDisappear 视图已经被从屏幕上移除,用户看不到这个视图了
3、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。
14,应用程序的生命周期
1,启动但还没进入状态保存 :
- (BOOL)application:(UIApplication *)application willFinishLaunchingWithOptions:(NSDictionary *)launchOptions
2,基本完成程序准备开始运行:
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
3,当应用程序将要入非活动状态执行,应用程序不接收消息或事件,比如来电话了:
- (void)applicationWillResignActive:(UIApplication *)application
4,当应用程序入活动状态执行,这个刚好跟上面那个方法相反:
- (void)applicationDidBecomeActive:(UIApplication *)application
5,当程序被推送到后台的时候调用。所以要设置后台继续运行,则在这个函数里面设置即可:
- (void)applicationDidEnterBackground:(UIApplication *)application
6,当程序从后台将要重新回到前台时候调用,这个刚好跟上面的那个方法相反:
- (void)applicationWillEnterForeground:(UIApplication *)application
7,当程序将要退出是被调用,通常是用来保存数据和一些退出前的清理工作:
- (void)applicationWillTerminate:(UIApplication *)application
15,判断view是不是指定视图的子视图
BOOL isView = [textView isDescendantOfView:self.view];
16,判断对象是否遵循了某协议
if ([self.selectedController conformsToProtocol:@protocol(RefreshPtotocol)]) {
[self.selectedController performSelector:@selector(onTriggerRefresh)];
}
17,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;
}
18,系统键盘通知消息
1、UIKeyboardWillShowNotification-将要弹出键盘
2、UIKeyboardDidShowNotification-显示键盘
3、UIKeyboardWillHideNotification-将要隐藏键盘
4、UIKeyboardDidHideNotification-键盘已经隐藏
5、UIKeyboardWillChangeFrameNotification-键盘将要改变frame
6、UIKeyboardDidChangeFrameNotification-键盘已经改变frame
19,关闭navigationController的滑动返回手势
self.navigationController.interactivePopGestureRecognizer.enabled = NO;
20,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];
}
21,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。
22,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;
}
23,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
24,宏定义检测block是否可用
#define BLOCK_EXEC(block, ...) if (block) { block(__VA_ARGS__); };
// 宏定义之前的用法
if (completionBlock) {
completionBlock(arg1, arg2);
}
// 宏定义之后的用法
BLOCK_EXEC(completionBlock, arg1, arg2);
时间: 2024-09-29 23:30:58