OC踩坑指南(不定期更新)

本文主要是介绍OC踩坑指南(不定期更新)，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

1.iOS11上上出现UIToolbar上添加按钮，button点击事件无法响应问题

解决办法： 在iOS11以上的情况下 UIToolbar的UIToolbarContentView会出现覆盖在视图最上层情况，导致后续添加的按钮无法点击，所以为了避免这种情况下按钮无法点击需要在将UIToolbar添加到UI层上之后立马[toolbar layoutIfNeeded];。降低UIToolbarContentView的层级关系

2.在iPhone5C上 [UIFont fontWithName:familyNamed size:font] 方法不会被正确执行

解决办法：需要修改为系统的[UIFont systemFontOfSize:font];

3.系统自带UIAlertController弹出延迟问题

解决办法：可使用回到主线程进行弹出，有效避免系统弹框延迟问题dispatch_async(dispatch_get_main_queue(), ^{[self presentViewController:alert animated:true completion:nil];});

4.WKWebView上使用自定义UIMenuController

小伙伴们可以测试一下，WKWebView正常情况下是无法取消掉系统自带的复制，粘贴，全选等选项的
如果当前WKWebView中没有弹出键盘需求的话可直接使用以下办法弹出自定义按钮
- (BOOL)canResignFirstResponder{if (_dismissSelf) {return YES;}return NO;
}- (void)viewWillDisappear:(BOOL)animated{[super viewWillDisappear:animated];self.dismissSelf = YES;
}- (void)viewWillAppear:(BOOL)animated {[super viewWillAppear:animated];self.dismissSelf = NO;
}
@warning _dismissSelf 这个布尔值的意义在为NO时，可展示自定义的UIMenuItem，
但是- (BOOL)canResignFirstResponder这个函数返回是全局都做修改的。
如果退出当前界面还是为NO的话，那么我们项目中所有的键盘弹出将不起作用

5.UISearchBar相关问题

-(UISearchBar *)poiSearchBar{if (!_poiSearchBar) {_poiSearchBar = [[UISearchBar alloc]init];_poiSearchBar.backgroundImage = [[UIImage alloc]init];_poiSearchBar.barTintColor = [UIColor uiColorFromString:@"#f0f3f8"];_poiSearchBar.placeholder = @"请输入检索信息";_poiSearchBar.delegate = self;_poiSearchBar.barStyle = UIBarStyleDefault;_poiSearchBar.tintColor = [UIColor redColor];[_poiSearchBar setImage:[UIImage imageNamed:@"search_Icon"] forSearchBarIcon:UISearchBarIconSearch state:UIControlStateNormal];// 设置圆角和边框颜色UITextField * searchF = [_poiSearchBar valueForKey:@"searchField"];// KVO获取私有变量if (searchF) {[searchF setBackgroundColor:[UIColor  uiColorFromString:@"#f0f3f8"]];[searchF setValue:[UIFont boldSystemFontOfSize:13] forKeyPath:@"_placeholderLabel.font"];//KVCsearchF.returnKeyType = UIReturnKeySearch;searchF.layer.cornerRadius = 5;searchF.layer.borderWidth = 1;searchF.layer.borderColor = [UIColor redColor].CGColor;searchF.layer.masksToBounds = YES;[searchF setTintColor:[UIColor uiColorFromString:@"#1997eb"]];}}return _poiSearchBar;}

搜索框上取消按钮-(void)searBarText:(UISearchBar*)searchBar{searchBar.showsCancelButton = YES;for (UIView * view in [[[searchBar subviews] objectAtIndex:0] subviews]) {if ([view isKindOfClass:[NSClassFromString(@"UINavigationButton")class]]) {UIButton * cancle = (UIButton *)view;cancle.hidden = NO;[cancle setTitle:@"取消" forState:UIControlStateNormal];[cancle setTitleColor:[UIColor uiColorFromString:@"#f0f3f8"] forState:UIControlStateNormal];cancle.enabled = YES;//系统默认为NO.为了达到没有输入文字直接点击取消可以返回之前的界面。而不是第一次点击取消会获取焦点走searchBarTextDidBeginEditing方法 。需要在找到取消按钮的时候设置为YEScancle.titleLabel.font = [UIFont systemFontOfSize:15];[cancle addTarget:self action:@selector(cancleButton:) forControlEvents:UIControlEventTouchUpInside];}}}

UISearchBar解析
(1)改变背景色
找到_searchbar.subviews 数组中的第一个view。自定义一个view添加背景色放在上变
(2)不显示背景色
样式中（searchBarStyle）选择 UISearchBarStyleMinimal //不显示背景色
(3)改变输入框的圆角
找到textfield  UITextfield * textF = [_searchBar valueForKey:”searchField”]navBo如果存在改变圆角。
(4)改变提示字体的大小
利用KVC 实现改变提示字体的大小
[_textfield setValue:[UIFont boldSystemFontOfSize:字体大小]

6.消除头部停留

-(void)scrollViewDidScroll:(UIScrollView*)scrollerView{CGFloat section = 区头高度if(scrollView.contentOffset.y < section && scrollView.contentOffset.y >0){scrollView.contentInset = UIEdgeInsetsMake(-scrollView.contentOffset.y,0,0,0)}else if {scrollView.contentInset = UIEdgeInsetMake(-section,0,0,0)}}

7.多个字符串拼接（举例以逗号拼接）

NSArray *strs = [@"a", @"b", @"c"];NSString *string = [strs componentsJoinedByString:@","];

8.多个字符串（单个）分隔 （举例以逗号分隔）

NSString *a = [[NSString alloc] initWithString : @"冬瓜，西瓜，火龙果，大头，小狗" ];NSArray *b = [a componentsSeparatedByString:@"，"];

9.截取字符串

- (NSString *)substringFromIndex:(NSUInteger)from; 从哪个位置其到尾
- (NSString *)substringToIndex:(NSUInteger)to; 从开头到哪个位置
- (NSString *)substringWithRange:(NSRange)range;  从哪到哪之间的位置

10.分隔指定字符串

NSArray *resultArr1 =     [stringcomponentsSeparatedByString:@"_"];

11.替换某一个字符串

NSString * string=@"2011-11-29";
string=[string stringByReplacingOccurrencesOfString:@"-"withString:@"/"]; 
结果： 2011/11/29

12.添加中划线

NSString *textStr = [NSString stringWithFormat:@"%@元", primeCost];//中划线NSDictionary *attribtDic = @{NSStrikethroughStyleAttributeName: [NSNumber numberWithInteger:NSUnderlineStyleSingle]};NSMutableAttributedString *attribtStr = [[NSMutableAttributedString alloc]initWithString:textStr attributes:attribtDic];// 赋值strikeLabel.attributedText = attribtStr;

13.添加下划线:

NSString *textStr = [NSString stringWithFormat:@"%@元", primeCost];// 下划线NSDictionary *attribtDic = @{NSUnderlineStyleAttributeName: [NSNumber numberWithInteger:NSUnderlineStyleSingle]};NSMutableAttributedString *attribtStr = [[NSMutableAttributedString alloc]initWithString:textStr attributes:attribtDic];//赋值underlineLabel.attributedText = attribtStr;

14.统一收起键盘

[[[UIApplication sharedApplication] keyWindow] endEditing:YES];

15.获取APP缓存大小，并清理

- (CGFloat)getCachSize {NSUInteger imageCacheSize = [[SDImageCache sharedImageCache] getSize];//获取自定义缓存大小//用枚举器遍历 一个文件夹的内容//1.获取 文件夹枚举器NSString *myCachePath = [NSHomeDirectory() stringByAppendingPathComponent:@"Library/Caches"];NSDirectoryEnumerator *enumerator = [[NSFileManager defaultManager] enumeratorAtPath:myCachePath];__block NSUInteger count = 0;//2.遍历for (NSString *fileName in enumerator) {NSString *path = [myCachePath stringByAppendingPathComponent:fileName];NSDictionary *fileDict = [[NSFileManager defaultManager] attributesOfItemAtPath:path error:nil];count += fileDict.fileSize;//自定义所有缓存大小}// 得到是字节  转化为MCGFloat totalSize = ((CGFloat)imageCacheSize+count)/1024/1024;return totalSize;
}
13.清理APP缓存
- (void)handleClearView {//删除两部分//1.删除 sd 图片缓存//先清除内存中的图片缓存[[SDImageCache sharedImageCache] clearMemory];//清除磁盘的缓存[[SDImageCache sharedImageCache] clearDisk];//2.删除自己缓存NSString *myCachePath = [NSHomeDirectory() stringByAppendingPathComponent:@"Library/Caches"];[[NSFileManager defaultManager] removeItemAtPath:myCachePath error:nil];
}

16.交换方法的实现

Class aClass = [self class]; SEL originalSelector = @selector(viewWillAppear:); SEL swizzledSelector = @selector(xxx_viewWillAppear:); Method originalMethod = class_getInstanceMethod(aClass, originalSelector); Method swizzledMethod = class_getInstanceMethod(aClass, swizzledSelector); BOOL didAddMethod = class_addMethod(aClass, originalSelector, method_getImplementation(swizzledMethod), method_getTypeEncoding(swizzledMethod)); if (didAddMethod) { class_replaceMethod(aClass, swizzledSelector, method_getImplementation(originalMethod), method_getTypeEncoding(originalMethod)); } else { method_exchangeImplementations(originalMethod, swizzledMethod); }

17.几个常用权限判断

 if ([CLLocationManager authorizationStatus] ==kCLAuthorizationStatusDenied) {NSLog(@"没有定位权限");}AVAuthorizationStatus statusVideo = [AVCaptureDevice authorizationStatusForMediaType:AVMediaTypeVideo];if (statusVideo == AVAuthorizationStatusDenied) {NSLog(@"没有摄像头权限");}//是否有麦克风权限AVAuthorizationStatus statusAudio = [AVCaptureDevice authorizationStatusForMediaType:AVMediaTypeAudio];if (statusAudio == AVAuthorizationStatusDenied) {NSLog(@"没有录音权限");}[PHPhotoLibrary requestAuthorization:^(PHAuthorizationStatus status) {if (status == PHAuthorizationStatusDenied) {NSLog(@"没有相册权限");}}];

18.升级cocoapods

在终端执行 sudo gem install -n / usr / local / bin cocoapods --pre

19.禁止手机睡眠

[UIApplication sharedApplication].idleTimerDisabled = YES;

20.导入自定义的字体库

1、找到你想用的字体的 ttf 格式，拖入工程
2、在工程的plist中增加一行数组，“Fonts provided by application”
3、为这个key添加一个item，value为你刚才导入的ttf文件名
4、直接使用即可：label.font = [UIFont fontWithName:@"你刚才导入的ttf文件名" size:20.0]；

21.将tableview滚动到顶部

[tableView setContentOffset:CGPointZero animated:YES];
或者
[tableView scrollRectToVisible:CGRectMake(0, 0, 1, 1) animated:YES];

22.自定义cell选中背景颜色

UIView *bgColorView = [[UIView alloc] init];
bgColorView.backgroundColor = [UIColor redColor];
[cell setSelectedBackgroundView:bgColorView];

23.UILabel设置文字描边

子类化UILabel，重写drawTextInRect方法
- (void)drawTextInRect:(CGRect)rect
{CGContextRef c = UIGraphicsGetCurrentContext();// 设置描边宽度CGContextSetLineWidth(c, 1);CGContextSetLineJoin(c, kCGLineJoinRound);CGContextSetTextDrawingMode(c, kCGTextStroke);// 描边颜色self.textColor = [UIColor redColor];[super drawTextInRect:rect];// 文本颜色self.textColor = [UIColor yellowColor];CGContextSetTextDrawingMode(c, kCGTextFill);[super drawTextInRect:rect];
}

24.手机摇一摇功能

1、打开摇一摇功能[UIApplication sharedApplication].applicationSupportsShakeToEdit = YES;
2、让需要摇动的控制器成为第一响应者
[self becomeFirstResponder];
3、实现以下方法// 开始摇动
- (void)motionBegan:(UIEventSubtype)motion withEvent:(UIEvent *)event
// 取消摇动
- (void)motionCancelled:(UIEventSubtype)motion withEvent:(UIEvent *)event
// 摇动结束
- (void)motionEnded:(UIEventSubtype)motion withEvent:(UIEvent *)event

25.获取view的坐标在整个window上的位置

// v上的(0, 0)点在toView上的位置
CGPoint point = [v convertPoint:CGPointMake(0, 0) toView:[UIApplication sharedApplication].windows.lastObject];
或者
CGPoint point = [v.superview convertPoint:v.frame.origin toView:[UIApplication sharedApplication].windows.lastObject];

26.在非ViewController的地方弹出UIAlertController对话框

//  最好抽成一个分类
UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"Title" message:@"message" preferredStyle:UIAlertControllerStyleAlert];
//...
id rootViewController = [UIApplication sharedApplication].delegate.window.rootViewController;
if([rootViewController isKindOfClass:[UINavigationController class]])
{rootViewController = ((UINavigationController *)rootViewController).viewControllers.firstObject;
}
if([rootViewController isKindOfClass:[UITabBarController class]])
{rootViewController = ((UITabBarController *)rootViewController).selectedViewController;
}
[rootViewController presentViewController:alertController animated:YES completion:nil];

27.设置tableView分割线颜色

[self.tableView setSeparatorColor:[UIColor myColor]];

28.设置tableviewcell分割线顶到头

- (void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath {[cell setSeparatorInset:UIEdgeInsetsZero];[cell setLayoutMargins:UIEdgeInsetsZero];cell.preservesSuperviewLayoutMargins = NO;
}- (void)viewDidLayoutSubviews {[self.tableView setSeparatorInset:UIEdgeInsetsZero];[self.tableView setLayoutMargins:UIEdgeInsetsZero];
}

29.在状态栏增加网络请求的菊花，类似safari加载网页的时候状态栏菊花

[UIApplication sharedApplication].networkActivityIndicatorVisible = YES;

30.检查一个rect是否包含一个point

// point是否在rect内
BOOL isContains = CGRectContainsPoint(rect, point);

31.在指定的宽度下，让UILabel自动设置最佳font

自适应宽度
label.adjustsFontSizeToFitWidth = YES;

32.为一个View添加虚线边框

结合使用，效果更佳CAShapeLayer *border = [CAShapeLayer layer];border.strokeColor = [UIColor colorWithRed:67/255.0f green:37/255.0f blue:83/255.0f alpha:1].CGColor;border.fillColor = nil;border.lineDashPattern = @[@4, @2];border.path = [UIBezierPath bezierPathWithRect:view.bounds].CGPath;border.frame = view.bounds;[view.layer addSublayer:border];

33.UITextView中打开或禁用复制，剪切，选择，全选等功能

// 继承UITextView重写这个方法
- (BOOL)canPerformAction:(SEL)action withSender:(id)sender
{
// 返回NO为禁用，YES为开启// 粘贴if (action == @selector(paste:)) return NO;// 剪切if (action == @selector(cut:)) return NO;// 复制if (action == @selector(copy:)) return NO;// 选择if (action == @selector(select:)) return NO;// 选中全部if (action == @selector(selectAll:)) return NO;// 删除if (action == @selector(delete:)) return NO;// 分享if (action == @selector(share)) return NO;return [super canPerformAction:action withSender:sender];
}

未完待续…

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