博客> iOS 知识-常用小技巧大杂烩
iOS 知识-常用小技巧大杂烩
2017-10-20 18:26 评论:10 阅读:4557 lishichao706
ios

开发过程中遇到的一些问题

网上查阅整理的一些问题

供大家参考,方便大家查阅

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]
// 利用这种方法设置颜色和透明值,可不影响子视图背景色
#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]

9. 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);
    }];
}

10. 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);

10. 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;
}

11. 播放声音

  #import<AVFoundation>
   //  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];

12. 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 xss=removed xss=removed xss=removed xss=removed xss=removed xss=removed xss=removed xss=removed xss=removed>> ~/.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。

25. 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;
}

26. 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

27. 宏定义检测block是否可用

#define BLOCK_EXEC&#40;block, ...&#41; 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&#40;completionBlock, arg1, arg2&#41;;

28. Debug栏打印时自动把Unicode编码转化成汉字

// 有时候我们在xcode中打印中文,会打印出Unicode编码,还需要自己去一些在线网站转换,有了插件就方便多了。
 DXXcodeConsoleUnicodePlugin 插件

29. 设置状态栏文字样式颜色

[[UIApplication sharedApplication] setStatusBarHidden:NO];
[[UIApplication sharedApplication] setStatusBarStyle:UIStatusBarStyleLightContent];

30. 自动生成模型代码的插件

// 可自动生成模型的代码,省去写模型代码的时间
ESJsonFormat-for-Xcode

31. iOS中的一些手势

轻击手势(TapGestureRecognizer)
轻扫手势(SwipeGestureRecognizer)
长按手势(LongPressGestureRecognizer)
拖动手势(PanGestureRecognizer)
捏合手势(PinchGestureRecognizer)
旋转手势(RotationGestureRecognizer)

32. iOS 开发中一些相关的路径

模拟器的位置:
/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs 

文档安装位置:
/Applications/Xcode.app/Contents/Developer/Documentation/DocSets

插件保存路径:
~/Library/ApplicationSupport/Developer/Shared/Xcode/Plug-ins

自定义代码段的保存路径:
~/Library/Developer/Xcode/UserData/CodeSnippets/ 
如果找不到CodeSnippets文件夹,可以自己新建一个CodeSnippets文件夹。

证书路径
~/Library/MobileDevice/Provisioning Profiles

33. 获取 iOS 路径的方法

获取家目录路径的函数
NSString *homeDir = NSHomeDirectory();

获取Documents目录路径的方法
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *docDir = [paths objectAtIndex:0];

获取Documents目录路径的方法
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES);
NSString *cachesDir = [paths objectAtIndex:0];

获取tmp目录路径的方法:
NSString *tmpDir = NSTemporaryDirectory();

34. 字符串相关操作

去除所有的空格
[str stringByReplacingOccurrencesOfString:@" " withString:@""]

去除首尾的空格
[str stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];

- (NSString *)uppercaseString; 全部字符转为大写字母
- (NSString *)lowercaseString 全部字符转为小写字母

35. CocoaPods pod install/pod update更新慢的问题

pod install --verbose --no-repo-update 
pod update --verbose --no-repo-update
如果不加后面的参数,默认会升级CocoaPods的spec仓库,加一个参数可以省略这一步,然后速度就会提升不少。

36. MRC和ARC混编设置方式

在XCode中targets的build phases选项下Compile Sources下选择 不需要arc编译的文件
双击输入 -fno-objc-arc 即可

MRC工程中也可以使用ARC的类,方法如下:
在XCode中targets的build phases选项下Compile Sources下选择要使用arc编译的文件
双击输入 -fobjc-arc 即可

37. 把tableview里cell的小对勾的颜色改成别的颜色

_mTableView.tintColor = [UIColor redColor];

38. 调整tableview的separaLine线的位置

tableView.separatorInset = UIEdgeInsetsMake(0, 100, 0, 0);

39. 设置滑动的时候隐藏navigationbar

navigationController.hidesBarsOnSwipe = Yes

40. 自动处理键盘事件,实现输入框防遮挡的插件

IQKeyboardManager
https://github.com/hackiftekhar/IQKeyboardManager

41. Quartz2D相关

图形上下是一个CGContextRef类型的数据。
图形上下文包含:
1,绘图路径(各种各样图形)
2,绘图状态(颜色,线宽,样式,旋转,缩放,平移)
3,输出目标(绘制到什么地方去?UIView、图片)

1,获取当前图形上下文
CGContextRef ctx = UIGraphicsGetCurrentContext();
2,添加线条
CGContextMoveToPoint(ctx, 20, 20);
3,渲染
CGContextStrokePath(ctx);
CGContextFillPath(ctx);
4,关闭路径
CGContextClosePath(ctx);
5,画矩形
CGContextAddRect(ctx, CGRectMake(20, 20, 100, 120));
6,设置线条颜色
[[UIColor redColor] setStroke];
7, 设置线条宽度
CGContextSetLineWidth(ctx, 20);
8,设置头尾样式
CGContextSetLineCap(ctx, kCGLineCapSquare);
9,设置转折点样式
CGContextSetLineJoin(ctx, kCGLineJoinBevel);
10,画圆
CGContextAddEllipseInRect(ctx, CGRectMake(30, 50, 100, 100));
11,指定圆心
CGContextAddArc(ctx, 100, 100, 50, 0, M_PI * 2, 1);
12,获取图片上下文
UIGraphicsGetImageFromCurrentImageContext();
13,保存图形上下文
CGContextSaveGState(ctx)
14,恢复图形上下文
CGContextRestoreGState(ctx)

42. 屏幕截图

    // 1. 开启一个与图片相关的图形上下文
    UIGraphicsBeginImageContextWithOptions(self.view.bounds.size,NO,0.0);

    // 2. 获取当前图形上下文
    CGContextRef ctx = UIGraphicsGetCurrentContext();

    // 3. 获取需要截取的view的layer
    [self.view.layer renderInContext:ctx];

    // 4. 从当前上下文中获取图片
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();

    // 5. 关闭图形上下文
    UIGraphicsEndImageContext();

    // 6. 把图片保存到相册
    UIImageWriteToSavedPhotosAlbum(image, nil, nil, nil);

43. 隐藏导航栏上的返回字体

//Swift
UIBarButtonItem.appearance().setBackButtonTitlePositionAdjustment(UIOffsetMake(0, -60), forBarMetrics: .Default)
//OC
[[UIBarButtonItem appearance] setBackButtonTitlePositionAdjustment:UIOffsetMake(0, -60) forBarMetrics:UIBarMetricsDefault];

44. 解决tableview的分割线短一截

-(void)viewDidLayoutSubviews{
if ([self.tableView respondsToSelector:@selector(setSeparatorInset:)])
{ 
[self.tableView setSeparatorInset:UIEdgeInsetsMake(0,0,0,0)];
}
if ([self.tableView respondsToSelector:@selector(setLayoutMargins:)]) 
{
[self.tableView setLayoutMargins:UIEdgeInsetsMake(0,0,0,0)]; 
}
}
-(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]; 
}
}

45. 动态隐藏NavigationBar

//1.当我们的手离开屏幕时候隐藏
- (void)scrollViewWillEndDragging:(UIScrollView *)scrollView withVelocity:(CGPoint)velocity targetContentOffset:(inout CGPoint *)targetContentOffset
{ 
if(velocity.y > 0) 
{
[self.navigationController setNavigationBarHidden:YES animated:YES];
} else {
[self.navigationController setNavigationBarHidden:NO animated:YES]; 
}
}
velocity.y这个量,在上滑和下滑时,变化极小(小数),但是因为方向不同,有正负之分,这就很好处理了。
//2.在滑动过程中隐藏
//像safari
(1) 
self.navigationController.hidesBarsOnSwipe = YES;
(2)
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
 CGFloat offsetY = scrollView.contentOffset.y + __tableView.contentInset.top;
 CGFloat panTranslationY = [scrollView.panGestureRecognizer translationInView:self.tableView].y;
 if (offsetY > 64) {
 if (panTranslationY > 0) 
{ 
//下滑趋势,显示 
[self.navigationController setNavigationBarHidden:NO animated:YES];
} else { 
//上滑趋势,隐藏 
[self.navigationController setNavigationBarHidden:YES animated:YES]; 
}
} else {
[self.navigationController setNavigationBarHidden:NO animated:YES]; 
}
}
这里的offsetY > 64只是为了在视图滑过navigationBar的高度之后才开始处理,防止影响展示效果。panTranslationY是scrollView的pan手势的手指位置的y值,可能不是太好,因为panTranslationY这个值在较小幅度上下滑动时,可能都为正或都为负,这就使得这一方式不太灵敏.

效果图

46. 设置导航栏透明

//方法一:设置透明度
[[[self.navigationController.navigationBar subviews]objectAtIndex:0] setAlpha:0.1];
//方法二:设置背景图片
/**
 * 设置导航栏,使其透明
 *
*/
- (void)setNavigationBarColor:(UIColor *)color targetController:(UIViewController *)targetViewController{
//导航条的颜色 以及隐藏导航条的颜色targetViewController.navigationController.navigationBar.shadowImage = [[UIImage alloc]init]; 
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(); [targetViewController.navigationController.navigationBar setBackgroundImage:theImage forBarMetrics:UIBarMetricsDefault];
}

47. 设置字体和行间距

//设置字体和行间距 
UILabel * lable = [[UILabel alloc]initWithFrame:CGRectMake(50, 100, 300, 200)]; 
lable.text = @"大家好,我是Frank_chun,在这里我们一起学习新的知识,总结我们遇到的那些坑,共同的学习,共同的进步,共同的努力,只为美好的明天!!!有问题一起相互的探讨--438637472!!!"; 
lable.numberOfLines = 0;
lable.font = [UIFont systemFontOfSize:12];
lable.backgroundColor = [UIColor grayColor]; 
[self.view addSubview:lable]; 
//设置每个字体之间的间距 
//NSKernAttributeName 这个对象所对应的值是一个NSNumber对象(包含小数),作用是修改默认字体之间的距离调整,值为0的话表示字距调整是禁用的; NSMutableAttributedString * str = [[NSMutableAttributedString alloc]initWithString:lable.text attributes:@{NSKernAttributeName:@(5.0)}];
//设置某写字体的颜色
//NSForegroundColorAttributeName 设置字体颜色
NSRange blueRange = NSMakeRange([[str string] rangeOfString:@"Frank_chun"].location, [[str string] rangeOfString:@"Frank_chun"].length); 
[str addAttribute:NSForegroundColorAttributeName value:[UIColor redColor] range:blueRange]; 
NSRange blueRange1 = NSMakeRange([[str string] rangeOfString:@"438637472"].location, [[str string] rangeOfString:@"438637472"].length);
[str addAttribute:NSForegroundColorAttributeName value:[UIColor redColor] range:blueRange1];
//设置每行之间的间距 
//NSParagraphStyleAttributeName 设置段落的样式
NSMutableParagraphStyle * par = [[NSMutableParagraphStyle alloc]init];
[par setLineSpacing:20];
//为某一范围内文字添加某个属性
//NSMakeRange表示所要的范围,从0到整个文本的长度
[str addAttribute:NSParagraphStyleAttributeName value:par range:NSMakeRange(0, lable.text.length)]; [lable setAttributedText:str];

效果图

48. 点击button倒计时

//第一种方法
//点击button倒计时
#import "ViewController.h"
@interface ViewController ()
@property (nonatomic, strong) UIButton * timeButton;
@property (nonatomic, strong) NSTimer * timer;
@property (nonatomic, strong)UIButton * btn;
@end@implementation ViewController
{ 
NSInteger _time;
}
- (void)viewDidLoad {
[super viewDidLoad]; 
_time = 5; 
self.btn = [UIButton buttonWithType:UIButtonTypeCustom]; _btn.backgroundColor = [UIColor orangeColor];
[_btn setTitle:@"获取验证码" forState:UIControlStateNormal]; _btn.titleLabel.font = [UIFont systemFontOfSize:15];
[_timeButton setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
[_btn addTarget:self action:@selector(btnAction:) forControlEvents:UIControlEventTouchUpInside];
[self refreshButtonWidth]; 
[self.view addSubview:self.btn];
}
- (void)refreshButtonWidth{ 
CGFloat width = 0; 
if (_btn.enabled){
 width = 100; 
} else { 
width = 200;
} 
_btn.center = CGPointMake(self.view.frame.size.width/2, 200);
_btn.bounds = CGRectMake(0, 0, width, 40); 
//每次刷新,保证区域正确
[_btn setBackgroundImage:[self imageWithColor:[UIColor orangeColor] andSize:_btn.frame.size] forState:UIControlStateNormal];
[_btn setBackgroundImage:[self imageWithColor:[UIColor lightGrayColor] andSize:_btn.frame.size] forState:UIControlStateDisabled];
}
- (UIImage *)imageWithColor:(UIColor *)color andSize:(CGSize)aSize{
 CGRect rect = CGRectMake(0.0f, 0.0f, aSize.width, aSize.height); UIGraphicsBeginImageContext(rect.size);
 CGContextRef context = UIGraphicsGetCurrentContext(); CGContextSetFillColorWithColor(context, [color CGColor]); CGContextFillRect(context, rect);
 UIImage *image = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext();
return image;
}
- (void)btnAction:(UIButton *)sender{
sender.enabled = NO;
[self refreshButtonWidth];
[sender setTitle:[NSString stringWithFormat:@"获取验证码(%zi)", _time] forState:UIControlStateNormal]; 
_timer = [NSTimer scheduledTimerWithTimeInterval:0.1 target:self selector:@selector(timeDown) userInfo:nil repeats:YES];
}
- (void)timeDown{ 
_time --;
 if (_time == 0) {
 [_btn setTitle:@"重新获取" forState:UIControlStateNormal]; _btn.enabled = YES; 
[self refreshButtonWidth]; 
[_timer invalidate]; 
_timer = nil; 
_time = 5 ; 
return; 
} 
[_btn setTitle:[NSString stringWithFormat:@"获取验证码(%zi)", _time] forState:UIControlStateNormal];
}
//第二种方法
#pragma mark -点击发送验证码
- (void)sendMessage:(UIButton *)btn{
if (self.phoneField.text.length == 0) { 
[self remindMessage:@"请输入正确的手机号"];
}else{ 
__block int timeout=60; 
//倒计时时间 
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0); dispatch_source_t _timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0,queue); dispatch_source_set_timer(_timer,dispatch_walltime(NULL, 0),1.0*NSEC_PER_SEC, 0);
 //每秒执行 
dispatch_source_set_event_handler(_timer, ^{ 
if(timeout<=0){ 
//倒计时结束,关闭 
dispatch_source_cancel(_timer); dispatch_async(dispatch_get_main_queue(), ^{ 
// 设置界面的按钮显示 根据自己需求设置 
[btn setTitle:@"发送验证码" forState:UIControlStateNormal]; btn.userInteractionEnabled = YES; 
}); 
}else{ 
int seconds = timeout % 60;
NSString *strTime = [NSString stringWithFormat:@"%d", seconds];
if ([strTime isEqualToString:@"0"]) {
 strTime = [NSString stringWithFormat:@"%d",60];
 } 
dispatch_async(dispatch_get_main_queue(), ^{ 
//设置界面的按钮显示 根据自己需求设置 
//NSLog(@"____%@",strTime);
[UIView beginAnimations:nil context:nil];
[UIView setAnimationDuration:1]; 
[btn setTitle:[NSString stringWithFormat:@"%@秒后重新发送",strTime] forState:UIControlStateNormal];
[UIView commitAnimations]; 
btn.userInteractionEnabled = NO;
 });
 timeout--;
 } 
}); 
dispatch_resume(_timer);
}

效果图

49. UITextField默认占位符是居中显示,让其居上显示

textField.contentVerticalAlignment = UIControlContentVerticalAlignmentTop;

50. 解决同时按两个按钮进两个view的问题

[button setExclusiveTouch:YES];

51. 图片拉伸

UIImage* img=[UIImage imageNamed:@"2.png"];//原图
UIEdgeInsets edge=UIEdgeInsetsMake(0, 10, 0,10);
//UIImageResizingModeStretch:拉伸模式,通过拉伸UIEdgeInsets指定的矩形区域来填充图片
//UIImageResizingModeTile:平铺模式,通过重复显示UIEdgeInsets指定的矩形区域来填充图
img= [img resizableImageWithCapInsets:edge resizingMode:UIImageResizingModeStretch];
self.imageView.image=img;

52. 修改textFieldplaceholder字体颜色和大小

textField.placeholder = @"username is in here!";  
[textField setValue:[UIColor redColor] forKeyPath:@"_placeholderLabel.textColor"];  
[textField setValue:[UIFont boldSystemFontOfSize:16] forKeyPath:@"_placeholderLabel.font"];

53. 修改状态栏字体颜色

只能设置两种颜色,黑色和白色,系统默认黑色
设置为白色方法:
(1)在plist里面添加Status bar style,值为UIStatusBarStyleLightContent(白色)或UIStatusBarStyleDefault(黑 色)
(2)在Info.plist中设置UIViewControllerBasedStatusBarAppearance 为NO

54. 去掉导航栏下边的黑线

[self.navigationController.navigationBar setBackgroundImage:[[UIImage alloc] init] forBarMetrics:UIBarMetricsDefault];
self.navigationController.navigationBar.shadowImage = [[UIImage alloc] init];

55. 修改pagecontrol颜色

_pageControl.currentPageIndicatorTintColor=SFQRedColor;
_pageControl.pageIndicatorTintColor=SFQGrayColor;

56. 去掉UITableView的section的粘性,使其不会悬停

//有时候使用UITableView所实现的列表,会使用到section,但是又不希望它粘在最顶上而是跟随滚动而消失或者出现
- (void)scrollViewDidScroll:(UIScrollView *)scrollView {  
    if (scrollView == _tableView) {  
        CGFloat sectionHeaderHeight = 36;

        if (scrollView.contentOffset.y <= sectionHeaderHeight && scrollView.contentOffset.y >= 0) {  
            scrollView.contentInset = UIEdgeInsetsMake(-scrollView.contentOffset.y, 0, 0, 0);  
        } else if (scrollView.contentOffset.y >= sectionHeaderHeight) {  
            scrollView.contentInset = UIEdgeInsetsMake(-sectionHeaderHeight, 0, 0, 0);  
        }  
    }  
}

57. 通过2D仿射函数实现小的动画效果(变大缩小) --可用于自定义pageControl中

[UIView animateWithDuration:0.3 animations:^{
       imageView.transform = CGAffineTransformMakeScale(2, 2);
       } completion:^(BOOL finished) {
       imageView.transform = CGAffineTransformMakeScale(1.0, 1.0);
       }];

58. UIImage与字符串互转

//图片转字符串  
-(NSString *)UIImageToBase64Str:(UIImage *) image  
{  
    NSData *data = UIImageJPEGRepresentation(image, 1.0f);  
    NSString *encodedImageStr = [data base64EncodedStringWithOptions:NSDataBase64Encoding64CharacterLineLength];  
    return encodedImageStr;  
}

//字符串转图片  
-(UIImage *)Base64StrToUIImage:(NSString *)_encodedImageStr  
{  
    NSData *_decodedImageData   = [[NSData alloc] initWithBase64Encoding:_encodedImageStr];  
    UIImage *_decodedImage      = [UIImage imageWithData:_decodedImageData];  
    return _decodedImage;  
}

59. 判断NSString中是否包含中文

-(BOOL)isChinese:(NSString *)str{
    NSString *match=@"(^[\u4e00-\u9fa5]+$)";
    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF matches %@", match];
    return [predicate evaluateWithObject:str];
}

60. NSDate与NSString的相互转化

-(NSString *)dateToString:(NSDate *)date {
  // 初始化时间格式控制器
  NSDateFormatter *matter = [[NSDateFormatter alloc] init];
  // 设置设计格式
  [matter setDateFormat:@"yyyy-MM-dd hh:mm:ss zzz"];
  // 进行转换
  NSString *dateStr = [matter stringFromDate:date];
  return dateStr;
}
-(NSDate *)stringToDate:(NSString *)dateStr {

  // 初始化时间格式控制器
  NSDateFormatter *matter = [[NSDateFormatter alloc] init];
  // 设置设计格式
  [matter setDateFormat:@"yyyy-MM-dd hh:mm:ss zzz"];
  // 进行转换
  NSDate *date = [matter dateFromString:dateStr];
  return date;
}

以上整理只为自己和大家方便查看,iOS中小技巧不计其数 如果大家有不错的代码和技巧,也可留言或私信我,然后加上, 持续更新中。。。。欢迎大家光临我的博客

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