★27个iOS开发中的小技巧 1、不想让TableView显示无用的Cell分割线怎么办？ self.tableView.tableFooterView = [[UIView alloc] init];
2、自定义了leftBarbuttonItem左滑返回手势失效了怎么办？ self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc] initWithImage:img style:UIBarButtonItemStylePlain target:self action:@selector(onBack:)]; self.navigationController.interactivePopGestureRecognizer.delegate = (id<uigesturerecognizerdelegate>)self;</uigesturerecognizerdelegate>
3、在ioS7中，如何检测系统自带ViewController手势返回结束？ -(void)navigationController:(UINavigationController*)navigationControllerwillShowViewController:(UIViewController*)viewControlleranimated:(BOOL)animated { id<UIViewControllerTransitionCoordinator>tc=navigationController.topViewController.transitionCoordinator; [tcnotifyWhenInteractionEndsUsingBlock:^(id<UIViewControllerTransitionCoordinatorContext>context){ NSLog(@"7:%i",[contextisCancelled]); }]; }
4、ScrollView莫名其妙不能在viewController划到顶怎么办？ self.automaticallyAdjustsScrollViewInsets = NO;
5、在不新建一个Cell的情况下，怎么调整separaLine的位置？ _myTableView.separatorInset = UIEdgeInsetsMake(0, 100, 0, 0);
6、怎么点击self.view就让键盘收起，需要添加一个tapGestures吗？ - (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { [self.view endEditing:YES]; }
7、怎么像safari一样滑动的时候隐藏navigationbar？ navigationController.hidesBarsOnSwipe = Yes
8、导航条返回键带的title太讨厌了，怎么让它消失？ [[UIBarButtonItem appearance] setBackButtonTitlePositionAdjustment:UIOffsetMake(0, -60) forBarMetrics:UIBarMetricsDefault];
9、CollectionView 怎么实现tableview那种悬停的header？ CSStickyHeaderFlowLayou
10、能不能只用一个pan手势来代替UISwipegesture的各个方向？ - (void)pan:(UIPanGestureRecognizer *)sender { typedef NS_ENUM(NSUInteger, UIPanGestureRecognizerDirection) { UIPanGestureRecognizerDirectionUndefined, UIPanGestureRecognizerDirectionUp, UIPanGestureRecognizerDirectionDown, UIPanGestureRecognizerDirectionLeft, UIPanGestureRecognizerDirectionRight }; static UIPanGestureRecognizerDirection direction = UIPanGestureRecognizerDirectionUndefined; switch (sender.state) { case UIGestureRecognizerStateBegan: { if (direction == UIPanGestureRecognizerDirectionUndefined) { CGPoint velocity = [sender velocityInView:recognizer.view]; BOOL isVerticalGesture = fabs(velocity.y) > fabs(velocity.x); if (isVerticalGesture) { if (velocity.y > 0) { direction = UIPanGestureRecognizerDirectionDown; } else { direction = UIPanGestureRecognizerDirectionUp; } } else { if (velocity.x > 0) { direction = UIPanGestureRecognizerDirectionRight; } else { direction = UIPanGestureRecognizerDirectionLeft; } } } break; } case UIGestureRecognizerStateChanged: { switch (direction) { case UIPanGestureRecognizerDirectionUp: { [self handleUpwardsGesture:sender]; break; } case UIPanGestureRecognizerDirectionDown: { [self handleDownwardsGesture:sender]; break; } case UIPanGestureRecognizerDirectionLeft: { [self handleLeftGesture:sender]; break; } case UIPanGestureRecognizerDirectionRight: { [self handleRightGesture:sender]; break; } default: { break; } } break; } case UIGestureRecognizerStateEnded: { direction = UIPanGestureRecognizerDirectionUndefined; break; } default: break; } }
11、怎么把tableview里cell的小对勾的颜色改成别的颜色？ _mTableView.tintColor = [UIColor redColor];
12、本来我的statusbar是lightcontent的，结果用UIImagePickerController会导致我的statusbar的样式变成黑色，怎么办？ - (void)navigationController:(UINavigationController *)navigationController willShowViewController:(UIViewController *)viewController animated:(BOOL)animated { [[UIApplication sharedApplication] setStatusBarStyle:UIStatusBarStyleLightContent]; }
13、怎么把我的navigationbar弄成透明的而不是带模糊的效果？ [self.navigationBar setBackgroundImage:[UIImage new] forBarMetrics:UIBarMetricsDefault]; self.navigationBar.shadowImage = [UIImage new]; self.navigationBar.translucent = YES;
14、怎么改变uitextfield placeholder的颜色和位置？ 继承uitextfield，重写这个方法： - (void) drawPlaceholderInRect:(CGRect)rect { [[UIColor blueColor] setFill]; [self.placeholder drawInRect:rect withFont:self.font lineBreakMode:UILineBreakModeTailTruncation alignment:self.textAlignment]; }
15、添加需要的不同语言字符串 简体中文Localizable.strings文件： "REMIND"="提示"; "OK"="确定"; "CANCEL"="取消"; "NetworkConnectError"="网络连接失败"; 英文版Localizable.strings文件： "REMIND"="Remind"; "OK"="OK"; "CANCEL"="Cancel"; "NetworkConnectError"="Cannot Connect Network"; 注意：不要遗漏结尾的分号“;”
16、使用国际化文件 UIAlertView *alert = [[UIAlertView alloc] initWithTitle:NSLocalizedString(@"REMIND", nil) message:NSLocalizedString(@"NetworkConnectError", nil) delegate:self cancelButtonTitle:NSLocalizedString(@"CANCEL", nil) otherButtonTitles:NSLocalizedString(@"OK", nil), nil]; [alert show];
17、遍历实践Tips 倒序遍历 NSArray和NSOrderedSet都支持使用reverseObjectEnumerator倒序遍历，如： NSArray *strings = @[@"1", @"2", @"3"]; for (NSString *string in [strings reverseObjectEnumerator]) { NSLog(@"%@", string); } 这个方法只在循环第一次被调用，所以不必担心循环每次计算的问题。 同时，使用enumerateObjectsWithOptions:NSEnumerationReverse也可以实现倒序遍历： [array enumerateObjectsWithOptions:NSEnumerationReverse usingBlock:^(Sark *sark, NSUInteger idx, BOOL *stop) { [sark doSomething]; }]; 使用block同时遍历字典key，value block版本的字典遍历可以同时取key和value（forin只能取key再手动取value），如： NSDictionary *dict = @{@"a": @"1", @"b": @"2"}; [dict enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) { NSLog(@"key: %@, value: %@", key, obj); }]; 对于耗时且顺序无关的遍历，使用并发版本： [array enumerateObjectsWithOptions:NSEnumerationConcurrent usingBlock:^(Sark *sark, NSUInteger idx, BOOL *stop) { [sark doSomethingSlow]; }];
18、如果在程序中想对某张图片进行处理的话（如得到某张图片的一部分）怎么做？ UIImage *image = [UIImage imageNamed:filename]; CGImageRef imageRef = image.CGImage; CGRect rect = CGRectMake(origin.x, origin.y ,size.width, size.height); CGImageRef imageRefRect = CGImageCreateWithImageInRect(imageRef, rect); UIImage *imageRect = [[UIImage alloc] initWithCGImage:imageRefRect];
19、如何判断邮箱输入的是否正确？ - (BOOL) validateEmail: (NSString *) candidate { NSString *emailRegex = @"[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+.[A-Za-z]{2,4}"; NSPredicate *emailTest = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", emailRegex]; return [emailTest evaluateWithObject:candidate]; }
20、如何把当前的视图作为照片保存到相册中去？ #import <QuartzCore/QuartzCore.h> UIGraphicsBeginImageContext(currentView.bounds.size); //currentView 当前的view [currentView.layer renderInContext:UIGraphicsGetCurrentContext()]; UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); UIImageWriteToSavedPhotosAlbum(viewIm
21、本地通知（类似于push通知）按home键到后台十秒后触发
UILocalNotification *notification=[[UILocalNotification alloc] init]; if (notification!=nil) { NSLog(@">> support local notification"); NSDate *now=[NSDate new]; notification.fireDate=[now addTimeInterval:10]; notification.timeZone=[NSTimeZone defaultTimeZone]; notification.alertBody=@"该去吃晚饭了！"; [[UIApplication sharedApplication].scheduleLocalNotification:notification];
22、捕获iphone通话事件
CTCallCenter *center = [[CTCallCenter alloc] init]; center.callEventHandler = ^(CTCall *call) { NSLog(@"call:%@", call.callState);
23、计算字符串的字数
-(int)calculateTextNumber:(NSString *)text { float number = 0.0; int index = 0; for (index; index < [text length]; index++) { NSString *protoText = [text substringToIndex:[text length] - index]; NSString *toChangetext = [text substringToIndex:[text length] -1 -index]; NSString *charater; if ([toChangetext length]==0) { charater = protoText; } else { NSRange range = [text rangeOfString:toChangetext]; charater = [protoText stringByReplacingCharactersInRange:range withString:@""]; } NSLog(charater); if ([charater lengthOfBytesUsingEncoding:NSUTF8StringEncoding] == 3) { number++; } else { number = number+0.5; } } return ceil(number); }
24、iPad隐藏键盘的同时触发方法 [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillHide:) name:UIKeyboardWillHideNotification object:nil]; - (IBAction)keyboardWillHide:(NSNotification *)note
25、设置时区 NSTimeZone *defaultTimeZone = [NSTimeZone defaultTimeZone]; NSTimeZone *tzGMT = [NSTimeZone timeZoneWithName:@"GMT"]; [NSTimeZone setDefaultTimeZone:tzGMT];
26、在程序中实现电话的拨打 //添加电话图标按钮 UIButton *btnPhone = [[UIButton buttonWithType:UIButtonTypeCustom] retain]; btnPhone.frame = CGRectMake(280,10,30,30); UIImage *image = [UIImage imageNamed:@"phone.png"]; [btnPhone setBackgroundImage:image forState:UIControlStateNormal]; //点击拨号按钮直接拨号 [btnPhone addTarget:self action:@selector(callAction:event:)forControlEvents:UIControlEventTouchUpInside]; [cell.contentView addSubview:btnPhone]; //cell是一个UITableViewCell //定义点击拨号按钮时的操作 - (void)callAction:(id)sender event:(id)event{ NSSet *touches = [event allTouches]; UITouch *touch = [touches anyObject]; CGPoint currentTouchPosition = [touch locationInView:self.listTable]; NSIndexPath *indexPath = [self.listTable indexPathForRowAtPoint: currentTouchPosition]; if (indexPath == nil) { return; } NSInteger section = [indexPath section]; NSUInteger row = [indexPath row]; NSDictionary *rowData = [datas objectAtIndex:row]; NSString *num = [[NSString alloc] initWithFormat:@"tel://%@",number]; //number为号码字符串 [[UIApplication sharedApplication] openURL:[NSURL URLWithString:num]]; //拨号 }
27、实现自定义的状态栏（遮盖状态栏） CGRect frame = {{0, 0}, {320, 20}}; UIWindow* wd = [[UIWindow alloc] initWithFrame:frame]; [wd setBackgroundColor:[UIColor clearColor]]; [wd setWindowLevel:UIWindowLevelStatusBar]; frame = CGRectMake(100, 0, 30, 20); UIImageView* img = [[UIImageView alloc] initWithFrame:frame]; [img setContentMode:UIViewContentModeCenter]; [img setImage:[UIImage imageNamed:@"00_0103.png"]]; [wd addSubview:img]; [wd makeKeyAndVisible]; [UIView beginAnimations:nil context:nil]; [UIView setAnimationDuration:2]; frame.origin.x += 150; [img setFrame:frame]; [UIView commitAnimations];