是否可以删除UITabBarItem中的图像并垂直alignment标题
我有一个UITabBar但我不想设置图像，我只是想设置标题，我希望这个标题垂直alignment。 这可能吗？
谢谢
从来没听说过。 我想你需要创build你的文本标签的图像（事先在你select的graphics工具中，或者你可以在运行时以编程方式创build它们）。
如果你想以编程的方式来做，像下面这样的方法可能会做到这一点。 它使用您传递的文本创build一个中心alignment的图像，执行单词换行。
UITabBarItem *item = [self.tabBar.items objectAtIndex:0]; item.image = [self makeThumbnailFromText:@"Tab Bar One"]; item.title = nil; item = [self.tabBar.items objectAtIndex:1]; item.image = [self makeThumbnailFromText:@"Tab Bar Two"]; item.title = nil;
这使用一个小方法，通过渲染传递给它的文本来创build一个位图。 您可能需要使用图像大小和字体大小来优化标签栏控制器图像。
- (UIImage *)makeThumbnailFromText:(NSString *)string { // some variables that control the size of the image we create, what font to use, etc. CGSize imageSize = CGSizeMake(60, 80); CGFloat fontSize = 13.0; NSString *fontName = @"Helvetica-Bold"; UIFont *font = [UIFont fontWithName:fontName size:fontSize]; CGFloat lineSpacing = fontSize * 1.2; // set up the context and the font UIGraphicsBeginImageContextWithOptions(imageSize, false, 0); NSDictionary *attributes = @{NSFontAttributeName: font}; // some variables we use for figuring out the words in the string and how to arrange them on lines of text NSArray <NSString *> *words = [string componentsSeparatedByString:@" "]; NSMutableArray <NSDictionary *> *lines = [NSMutableArray array]; NSString *lineThusFar; CGSize sizeThusFar = CGSizeZero; // let's figure out the lines by examining the size of the rendered text and seeing whether it fits or not and // figure out where we should break our lines (as well as using that to figure out how to center the text) for (NSString *word in words) { NSString *currentLine = lineThusFar ? [NSString stringWithFormat:@"%@ %@", lineThusFar, word] : word; CGSize size = [currentLine sizeWithAttributes: attributes]; if (size.width > imageSize.width && lineThusFar) { [lines addObject:@{@"text": lineThusFar, @"size": [NSValue valueWithCGSize: sizeThusFar]}]; lineThusFar = word; sizeThusFar = [word sizeWithAttributes: attributes]; } else { lineThusFar = currentLine; sizeThusFar = size; } } if (lineThusFar) { [lines addObject:@{@"text": lineThusFar, @"size": [NSValue valueWithCGSize: sizeThusFar]}]; } // now write the lines of text we figured out above CGFloat totalSize = (lines.count - 1) * lineSpacing + fontSize; CGFloat topMargin = (imageSize.height - totalSize) / 2.0; for (NSInteger i = 0; i < lines.count; i++) { CGFloat x = (imageSize.width - [lines[i][@"size"] CGSizeValue].width) / 2.0; CGFloat y = topMargin + i * lineSpacing; [lines[i][@"text"] drawAtPoint:CGPointMake(x, y) withAttributes: attributes]; } UIImage *image = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); return image; }
在Swift中，这可能看起来像：
func makeThumbnailFromText(text: String) -> UIImage { // some variables that control the size of the image we create, what font to use, etc. struct LineOfText { var string: String var size: CGSize } let imageSize = CGSize(width: 60, height: 80) let fontSize: CGFloat = 13.0 let fontName = "Helvetica-Bold" let font = UIFont(name: fontName, size: fontSize)! let lineSpacing = fontSize * 1.2 // set up the context and the font UIGraphicsBeginImageContextWithOptions(imageSize, false, 0) let attributes = [NSFontAttributeName: font] // some variables we use for figuring out the words in the string and how to arrange them on lines of text let words = text.componentsSeparatedByString(" ") var lines = [LineOfText]() var lineThusFar: LineOfText? // let's figure out the lines by examining the size of the rendered text and seeing whether it fits or not and // figure out where we should break our lines (as well as using that to figure out how to center the text) for word in words { let currentLine = lineThusFar?.string == nil ? word : "\(lineThusFar!.string) \(word)" let size = currentLine.sizeWithAttributes(attributes) if size.width > imageSize.width && lineThusFar != nil { lines.append(lineThusFar!) lineThusFar = LineOfText(string: word, size: word.sizeWithAttributes(attributes)) } else { lineThusFar = LineOfText(string: currentLine, size: size) } } if lineThusFar != nil { lines.append(lineThusFar!) } // now write the lines of text we figured out above let totalSize = CGFloat(lines.count - 1) * lineSpacing + fontSize let topMargin = (imageSize.height - totalSize) / 2.0 for (index, line) in lines.enumerate() { let x = (imageSize.width - line.size.width) / 2.0 let y = topMargin + CGFloat(index) * lineSpacing line.string.drawAtPoint(CGPoint(x: x, y: y), withAttributes: attributes) } let image = UIGraphicsGetImageFromCurrentImageContext() UIGraphicsEndImageContext() return image }
和
var item = tabBar.items![0] item.image = makeThumbnailFromText("Tab Bar One") item.title = nil; item = tabBar.items![1] item.image = makeThumbnailFromText("Tab Bar Two") item.title = nil;
快3
/ /我的中心项目是图像只rest选项卡栏项目是文本只
let tabs = CustomTabBarController(); tabs.viewControllers = [ViewControllerOne(),ViewControllerTwo(),ViewControllerThree()] let tabbar = tabs.tabBar; tabbar.backgroundColor = UIColor.white let tabOne = tabbar.items![0] tabOne.title = "One" let tabTwo = tabbar.items![1] tabTwo.imageInsets = UIEdgeInsetsMake(6, 0, -6, 0); tabTwo.image = UIImage(named: "tab_icon.png") let tabThree = tabbar.items![2] tabThree.title = "Three"
//和我的CustomTabBarController中
import UIKit class CustomTabBarController: UITabBarController { override func viewDidLoad() { super.viewDidLoad() UITabBar.appearance().tintColor = UIColor.black UITabBarItem.appearance().titlePositionAdjustment = UIOffset(horizontal: 0, vertical: -15) } override func viewWillAppear(_ animated: Bool) { super.viewWillAppear(true) self.selectedIndex = 1; } override var selectedViewController: UIViewController? { didSet { guard let viewControllers = viewControllers else { return } for viewController in viewControllers { if viewController == selectedViewController { let selected: [String: AnyObject] = [NSFontAttributeName:fontForTimesRoman(withStyle: "bold", andFontsize: 12), NSForegroundColorAttributeName: UIColor.black] viewController.tabBarItem.setTitleTextAttributes(selected, for: .normal) } else { let normal: [String: AnyObject] = [NSFontAttributeName: fontForTimesRoman(withStyle: "regular", andFontsize: 12), NSForegroundColorAttributeName: UIColor.gray] viewController.tabBarItem.setTitleTextAttributes(normal, for: .normal) } } } } func fontForTimesRoman(withStyle style: String, andFontsize size: CGFloat) -> UIFont { if (style == "bold") { return UIFont(name: "TimesNewRomanPS-BoldMT", size: size)! } else if(style == "italic"){ return UIFont(name: "TimesNewRomanPS-ItalicMT", size: size)! } else{ return UIFont(name: "TimesNewRomanPSMT", size: size)! } } }