这是我的Objective-C代码，我用来为我的自定义UIView加载一个笔尖：
-(id)init{
NSArray *subviewArray = [[NSBundle mainBundle] loadNibNamed:@"myXib" owner:self options:nil];
return [subviewArray objectAtIndex:0];
}
Swift中的等效代码是什么？
原始方案
.
class SomeView: UIView {
required init(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
NSBundle.mainBundle().loadNibNamed("SomeView", owner: self, options: nil)
self.addSubview(self.view); // adding the top level view to the view hierarchy
}
...
}
请注意，这样我获得了一个从nib加载自身的类。然后，只要UIView可以在项目中使用（在界面生成器中或以编程方式），我就可以将SomeView用作类。
更新 - 使用Swift 3语法
在以下扩展中加载xib将被写为实例方法，然后可以由上面的初始化程序使用：
extension UIView {
@discardableResult // 1
func fromNib<T : UIView>() -> T? { // 2
guard let contentView = Bundle(for: type(of: self)).loadNibNamed(String(describing: type(of: self)), owner: self, options: nil)?.first as? T else { // 3
// xib not loaded, or its top view is of the wrong type
return nil
}
self.addSubview(contentView) // 4
contentView.translatesAutoresizingMaskIntoConstraints = false // 5
contentView.layoutAttachAll(to: self) // 6
return contentView // 7
}
}
调用方法可能如下所示：
final class SomeView: UIView { // 1.
required init?(coder aDecoder: NSCoder) { // 2 - storyboard initializer
super.init(coder: aDecoder)
fromNib() // 5.
}
init() { // 3 - programmatic initializer
super.init(frame: CGRect.zero) // 4.
fromNib() // 6.
}
// other methods ...
}
信用：在此解决方案中使用通用扩展程序的灵感来自Robert的答案。
编辑将“视图”更改为“contentView”以避免混淆。还将数组下标更改为“.first”。
使用Swift执行此操作的一个好方法是使用枚举。
enum Views: String {
case view1 = "View1" // Change View1 to be the name of your nib
case view2 = "View2" // Change View2 to be the name of another nib
func getView() -> UIView? {
return NSBundle.mainBundle().loadNibNamed(self.rawValue, owner: nil, options: nil).first as? UIView
}
}
然后在您的代码中，您可以简单地使用：
let view = Views.view1.getView()
let subviewArray = NSBundle.mainBundle().loadNibNamed("myXib", owner: self, options: nil)
return subviewArray[0]
我更喜欢这个解决方案（基于@ GK100的答案）：
init或init:frame: CGRect初始化器中。没有必要为“自我”分配任何东西。加载XIB后，所有插座都会连接，包括顶层视图。唯一缺少的是将顶视图添加到视图层次结构中：
class SomeView: UIView {
override init(frame: CGRect) {
super.init(frame: frame)
NSBundle.mainBundle().loadNibNamed("SomeObject", owner: self, options: nil)
self.addSubview(self.view); // adding the top level view to the view hierarchy
}
required init(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
NSBundle.mainBundle().loadNibNamed("SomeObject", owner: self, options: nil)
self.addSubview(self.view); // adding the top level view to the view hierarchy
}
...
}
Swift 3版本的Logan的回答
extension UIView {
public class func fromNib(nibName: String? = nil) -> Self {
return fromNib(nibName: nibName, type: self)
}
public class func fromNib<T: UIView>(nibName: String? = nil, type: T.Type) -> T {
return fromNib(nibName: nibName, type: T.self)!
}
public class func fromNib<T: UIView>(nibName: String? = nil, type: T.Type) -> T? {
var view: T?
let name: String
if let nibName = nibName {
name = nibName
} else {
name = self.nibName
}
if let nibViews = Bundle.main.loadNibNamed(name, owner: nil, options: nil) {
for nibView in nibViews {
if let tog = nibView as? T {
view = tog
}
}
}
return view
}
public class var nibName: String {
return "\(self)".components(separatedBy: ".").first ?? ""
}
public class var nib: UINib? {
if let _ = Bundle.main.path(forResource: nibName, ofType: "nib") {
return UINib(nibName: nibName, bundle: nil)
} else {
return nil
}
}
}
斯威夫特4
不要忘记写“.first as？CustomView”。
if let customView = Bundle.main.loadNibNamed("myXib", owner: self, options: nil)?.first as? CustomView {
self.view.addSubview(customView)
}
如果你想在任何地方使用
最佳解决方案是Robert Gummesson的回答。
extension UIView {
class func fromNib<T: UIView>() -> T {
return Bundle.main.loadNibNamed(String(describing: T.self), owner: nil, options: nil)![0] as! T
}
}
然后像这样称呼它：
let myCustomView: CustomView = UIView.fromNib()
我这样做：
if let myView = UINib.init(nibName: "MyView", bundle: nil).instantiate(withOwner: self)[0] as? MyView {
// Do something with myView
}
此示例使用主包中的笔尖“MyView.xib”中的第一个视图。但您可以更改索引，笔尖名称或包（默认情况下为main）。
我曾经把视图唤醒到视图init方法或者像上面的解决方案那样制作通用方法（顺便说一句，它是聪明的），但我不再这样做了。
这样我可以使用不同的布局或特征，同时保持相同的视图逻辑和代码。
我发现更容易让工厂对象（通常是将使用视图的viewController）根据需要创建它。有时你需要一个拥有者（通常当创建的视图有一个连接到创建者的插座时），有时候不是..
这可能就是为什么Apple在其UIView类中没有包含initFromNib方法的原因......
举一个基层的例子，你不知道你是如何出生的。你刚出生。观点也是如此;）
您所要做的就是在UIView类中调用init方法。
这样做：
class className: UIView {
@IBOutlet var view: UIView!
override init(frame: CGRect) {
super.init(frame: frame)
setup()
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)!
}
func setup() {
UINib(nibName: "nib", bundle: nil).instantiateWithOwner(self, options: nil)
addSubview(view)
view.frame = self.bounds
}
}
现在，如果要将此视图添加为视图控制器中的子视图，请在视图controller.swift文件中执行此操作：
self.view.addSubview(className())
这是一种使用协议和协议扩展（Swift 4.2）以编程方式加载视图的简洁且声明性的方式：
protocol XibLoadable {
associatedtype CustomViewType
static func loadFromXib() -> CustomViewType
}
extension XibLoadable where Self: UIView {
static func loadFromXib() -> Self {
let nib = UINib(nibName: "\(self)", bundle: Bundle(for: self))
guard let customView = nib.instantiate(withOwner: self, options: nil).first as? Self else {
// your app should crash if the xib doesn't exist
preconditionFailure("Couldn't load xib for view: \(self)")
}
return customView
}
}
你可以像这样使用它：
// don't forget you need a xib file too
final class MyView: UIView, XibLoadable { ... }
// and when you want to use it
let viewInstance = MyView.loadFromXib()
一些额外的考虑：
Custom Class设置（以及从那里设置的outlet / actions），而不是文件所有者。与上面的一些答案类似，但更加一致的Swift3 UIView扩展：
extension UIView {
class func fromNib<A: UIView> (nibName name: String, bundle: Bundle? = nil) -> A? {
let bundle = bundle ?? Bundle.main
let nibViews = bundle.loadNibNamed(name, owner: self, options: nil)
return nibViews?.first as? A
}
class func fromNib<T: UIView>() -> T? {
return fromNib(nibName: String(describing: T.self), bundle: nil)
}
}
这样可以方便地从自己命名的nib加载类，也可以从其他nibs / bundle加载类。
您可以通过storyboard执行此操作，只需为视图添加适当的约束。你可以通过继承你自己的任何视图来轻松地做到这一点，比如BaseView：
Objective-C的
BaseView.h
/*!
@class BaseView
@discussion Base View for getting view from xibFile
@availability ios7 and later
*/
@interface BaseView : UIView
@end
BaseView.m
#import "BaseView.h"
@implementation BaseView
#pragma mark - Public
- (instancetype)initWithCoder:(NSCoder *)coder
{
self = [super initWithCoder:coder];
if (self) {
[self prepareView];
}
return self;
}
#pragma mark - LifeCycle
- (instancetype)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
[self prepareView];
}
return self;
}
#pragma mark - Private
- (void)prepareView
{
NSArray *nibsArray = [[NSBundle mainBundle] loadNibNamed:NSStringFromClass([self class]) owner:self options:nil];
UIView *view = [nibsArray firstObject];
view.translatesAutoresizingMaskIntoConstraints = NO;
[self addSubview:view];
[self addConstraintsForView:view];
}
#pragma mark - Add constraints
- (void)addConstraintsForView:(UIView *)view
{
[self addConstraints:@[[NSLayoutConstraint constraintWithItem:view
attribute:NSLayoutAttributeBottom
relatedBy:NSLayoutRelationEqual
toItem:self attribute:NSLayoutAttributeBottom
multiplier:1.0
constant:0],
[NSLayoutConstraint constraintWithItem:view
attribute:NSLayoutAttributeTop
relatedBy:NSLayoutRelationEqual
toItem:self attribute:NSLayoutAttributeTop
multiplier:1.0
constant:0],
[NSLayoutConstraint constraintWithItem:view
attribute:NSLayoutAttributeLeft
relatedBy:NSLayoutRelationEqual
toItem:self attribute:NSLayoutAttributeLeft
multiplier:1.0
constant:0],
[NSLayoutConstraint constraintWithItem:view
attribute:NSLayoutAttributeRight
relatedBy:NSLayoutRelationEqual
toItem:self attribute:NSLayoutAttributeRight
multiplier:1.0
constant:0]
]];
}
@end
斯威夫特4
import UIKit
class BaseView : UIView {
// MARK: - LifeCycle
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
prepareView()
}
override init(frame: CGRect) {
super.init(frame: frame)
prepareView()
}
internal class func xibName() -> String {
return String(describing: self)
}
// MARK: - Private
fileprivate func prepareView() {
let nameForXib = BaseView.xibName()
let nibs = Bundle.main.loadNibNamed(nameForXib, owner: self, options: nil)
if let view = nibs?.first as? UIView {
view.backgroundColor = UIColor.clear
view.translatesAutoresizingMaskIntoConstraints = false
addSubviewWithConstraints(view, offset: false)
}
}
}
UIView+Subview
public extension UIView {
// MARK: - UIView+Extensions
public func addSubviewWithConstraints(_ subview:UIView, offset:Bool = true) {
subview.translatesAutoresizingMaskIntoConstraints = false
let views = [
"subview" : subview
]
addSubview(subview)
var constraints = NSLayoutConstraint.constraints(withVisualFormat: offset ? "H:|-[subview]-|" : "H:|[subview]|", options: [.alignAllLeading, .alignAllTrailing], metrics: nil, views: views)
constraints.append(contentsOf: NSLayoutConstraint.constraints(withVisualFormat: offset ? "V:|-[subview]-|" : "V:|[subview]|", options: [.alignAllTop, .alignAllBottom], metrics: nil, views: views))
NSLayoutConstraint.activate(constraints)
}
}
我提供2种变体如何添加约束 - 常见的和可视化格式语言 - 选择你想要的任何:)
此外，默认情况下假设xib名称与实现类名称相同。如果不是 - 只需更改xibName参数。
如果您从BaseView继承您的视图 - 您可以轻松地放置任何视图并在IB中指定类。
我的贡献：
extension UIView {
class func fromNib<T: UIView>() -> T {
return Bundle.main.loadNibNamed(String(describing: T.self), owner: nil, options: nil)![0] as! T
}
}
然后像这样称呼它：
let myCustomView: CustomView = UIView.fromNib()
..甚至：
let myCustomView: CustomView = .fromNib()
class func loadFromNib<T: UIView>() -> T {
let nibName = String(describing: self)
return Bundle.main.loadNibNamed(nibName, owner: nil, options: nil)![0] as! T
}
基于Logan答案的更强大的版本
extension UIView {
public class func fromNib(nibName: String? = nil) -> Self {
return fromNib(nibName: nibName, type: self)
}
public class func fromNib<T: UIView>(nibName: String? = nil, type: T.Type) -> T {
return fromNib(nibName: nibName, type: T.self)!
}
public class func fromNib<T: UIView>(nibName: String? = nil, type: T.Type) -> T? {
var view: T?
let name: String
if let nibName = nibName {
name = nibName
} else {
name = self.nibName
}
if let nibViews = nibBundle.loadNibNamed(name, owner: nil, options: nil) {
if nibViews.indices.contains(nibIndex), let tog = nibViews[nibIndex] as? T {
view = tog
}
}
return view
}
public class var nibName: String {
return "\(self)".components(separatedBy: ".").first ?? ""
}
public class var nibIndex: Int {
return 0
}
public class var nibBundle: Bundle {
return Bundle.main
}
}
而你可以使用喜欢
class BaseView: UIView {
override class var nibName: String { return "BaseView" }
weak var delegate: StandardStateViewDelegate?
}
class ChildView: BaseView {
override class var nibIndex: Int { return 1 }
}
最方便的实现。在这里你需要两个方法，以便直接返回你的类的对象，而不是UIView。
extension UIView {
class var viewId: String {
return String(describing: self)
}
static func instance(from bundle: Bundle? = nil, nibName: String? = nil,
owner: Any? = nil, options: [AnyHashable : Any]? = nil) -> Self? {
return instancePrivate(from: bundle ?? Bundle.main,
nibName: nibName ?? viewId,
owner: owner,
options: options)
}
private static func instancePrivate<T: UIView>(from bundle: Bundle, nibName: String,
owner: Any?, options: [AnyHashable : Any]?) -> T? {
guard
let views = bundle.loadNibNamed(nibName, owner: owner, options: options),
let view = views.first(where: { $0 is T }) as? T else { return nil }
return view
}
}
例：
guard let customView = CustomView.instance() else { return }
//Here customView has CustomView class type, not UIView.
print(customView is CustomView) // true
如果你希望Swift UIView子类完全是自包含的，并且能够使用init或init（frame :)实例化而不暴露使用Nib的实现细节，那么你可以使用协议扩展来实现这一点。此解决方案避免了许多其他解决方案所建议的嵌套UIView层次结构。
public class CustomView: UIView {
@IBOutlet weak var nameLabel: UILabel!
@IBOutlet weak var valueLabel: UILabel!
public convenience init() {
self.init(frame: CGRect.zero)
}
public override convenience init(frame: CGRect) {
self.init(internal: nil)
self.frame = frame
}
public required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
commonInit()
}
fileprivate func commonInit() {
}
}
fileprivate protocol _CustomView {
}
extension CustomView: _CustomView {
}
fileprivate extension _CustomView {
// Protocol extension initializer - has the ability to assign to self, unlike
// class initializers. Note that the name of this initializer can be anything
// you like, here we've called it init(internal:)
init(internal: Int?) {
self = Bundle.main.loadNibNamed("CustomView", owner:nil, options:nil)![0] as! Self;
}
}
这是一个使用泛型从笔尖加载UIView的扩展
public extension UIView {
public class func fromNib(nibNameOrNil: String? = nil) -> Self {
return fromNib(nibNameOrNil, type: self)
}
public class func fromNib<T : UIView>(nibNameOrNil: String? = nil, type: T.Type) -> T {
let v: T? = fromNib(nibNameOrNil, type: T.self)
return v!
}
public class func fromNib<T : UIView>(nibNameOrNil: String? = nil, type: T.Type) -> T? {
var view: T?
let name: String
if let nibName = nibNameOrNil {
name = nibName
} else {
// Most nibs are demangled by practice, if not, just declare string explicitly
name = nibName
}
let nibViews = NSBundle.mainBundle().loadNibNamed(name, owner: nil, options: nil)
for v in nibViews {
if let tog = v as? T {
view = tog
}
}
return view
}
public class var nibName: String {
let name = "\(self)".componentsSeparatedByString(".").first ?? ""
return name
}
public class var nib: UINib? {
if let _ = NSBundle.mainBundle().pathForResource(nibName, ofType: "nib") {
return UINib(nibName: nibName, bundle: nil)
} else {
return nil
}
}
}
我更喜欢这个，因为它不需要在笔尖中进行任何额外的设置。它基于通用命名约定，因此如果您的类是CustomView，并且它匹配名为：CustomView的nib，您可以这样做：
let myCustomView = CustomView.fromNib()
// or if you're unsure whether or not the nib exists
let myCustomView: CustomView? = CustomView.fromNib()
如果您因任何原因需要具体了解nib名称，请传递一个字符串arg：
let myCustomView = MyCustomView.fromNib("non-conventional-name")
已知的问题
使用私有视图类似乎会导致问题。这似乎是一个系统问题。
尝试以下代码。
var uiview :UIView?
self.uiview = NSBundle.mainBundle().loadNibNamed("myXib", owner: self, options: nil)[0] as? UIView
编辑：
import UIKit
class TestObject: NSObject {
var uiview:UIView?
init() {
super.init()
self.uiview = NSBundle.mainBundle().loadNibNamed("myXib", owner: self, options: nil)[0] as? UIView
}
}
我通过以下代码用Swift实现了这一点：
class Dialog: UIView {
@IBOutlet var view:UIView!
override init(frame: CGRect) {
super.init(frame: frame)
self.frame = UIScreen.mainScreen().bounds
NSBundle.mainBundle().loadNibNamed("Dialog", owner: self, options: nil)
self.view.frame = UIScreen.mainScreen().bounds
self.addSubview(self.view)
}
required init(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
}
}
不要忘记将XIB视图插座连接到swift中定义的视图插座。您还可以将First Responder设置为您的自定义类名称，以开始连接任何其他插座。
希望这可以帮助！
在Xcode 7 beta 4，Swift 2.0和iOS9 SDK中测试过。以下代码将xib分配给uiview。您可以在故事板中使用此自定义xib视图，也可以访问IBOutlet对象。
import UIKit
@IBDesignable class SimpleCustomView:UIView
{
var view:UIView!;
@IBOutlet weak var lblTitle: UILabel!
@IBInspectable var lblTitleText : String?
{
get{
return lblTitle.text;
}
set(lblTitleText)
{
lblTitle.text = lblTitleText!;
}
}
override init(frame: CGRect) {
super.init(frame: frame)
loadViewFromNib ()
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
loadViewFromNib ()
}
func loadViewFromNib() {
let bundle = NSBundle(forClass: self.dynamicType)
let nib = UINib(nibName: "SimpleCustomView", bundle: bundle)
let view = nib.instantiateWithOwner(self, options: nil)[0] as! UIView
view.frame = bounds
view.autoresizingMask = [.FlexibleWidth, .FlexibleHeight]
self.addSubview(view);
}
}
以编程方式访问自定义视图
self.customView = SimpleCustomView(frame: CGRectMake(100, 100, 200, 200))
self.view.addSubview(self.customView!);
Swift 4协议扩展
public protocol NibInstantiatable {
static func nibName() -> String
}
extension NibInstantiatable {
static func nibName() -> String {
return String(describing: self)
}
}
extension NibInstantiatable where Self: UIView {
static func fromNib() -> Self {
let bundle = Bundle(for: self)
let nib = bundle.loadNibNamed(nibName(), owner: self, options: nil)
return nib!.first as! Self
}
}
采用
class MyView: UIView, NibInstantiatable {
}
此实现假定Nib与UIView类具有相同的名称。防爆。 MyView.xib。您可以通过在MyView中实现nibName（）来返回与默认协议扩展实现不同的名称来修改此行为。
在xib中，文件所有者是MyView，根视图类是MyView。
用法
let view = MyView.fromNib()
如果您的项目中有很多自定义视图，则可以创建类似UIViewFromNib的类
斯威夫特2.3
class UIViewFromNib: UIView {
var contentView: UIView!
var nibName: String {
return String(self.dynamicType)
}
//MARK:
override init(frame: CGRect) {
super.init(frame: frame)
loadViewFromNib()
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
loadViewFromNib()
}
//MARK:
private func loadViewFromNib() {
contentView = NSBundle.mainBundle().loadNibNamed(nibName, owner: self, options: nil)[0] as! UIView
contentView.autoresizingMask = [.FlexibleWidth, .FlexibleHeight]
contentView.frame = bounds
addSubview(contentView)
}
}
斯威夫特3
class UIViewFromNib: UIView {
var contentView: UIView!
var nibName: String {
return String(describing: type(of: self))
}
//MARK:
override init(frame: CGRect) {
super.init(frame: frame)
loadViewFromNib()
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
loadViewFromNib()
}
//MARK:
func loadViewFromNib() {
contentView = Bundle.main.loadNibNamed(nibName, owner: self, options: nil)?[0] as! UIView
contentView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
contentView.frame = bounds
addSubview(contentView)
}
}
并且在每个类中只从UIViewFromNib继承，如果nibName文件具有不同的名称，您也可以覆盖.xib属性：
class MyCustomClass: UIViewFromNib {
}
建立在上述解决方案之上。
这将适用于所有项目包，并且在调用fromNib（）时不需要泛型。
斯威夫特2
extension UIView {
public class func fromNib() -> Self {
return fromNib(nil)
}
public class func fromNib(nibName: String?) -> Self {
func fromNibHelper<T where T : UIView>(nibName: String?) -> T {
let bundle = NSBundle(forClass: T.self)
let name = nibName ?? String(T.self)
return bundle.loadNibNamed(name, owner: nil, options: nil)?.first as? T ?? T()
}
return fromNibHelper(nibName)
}
}
斯威夫特3
extension UIView {
public class func fromNib() -> Self {
return fromNib(nibName: nil)
}
public class func fromNib(nibName: String?) -> Self {
func fromNibHelper<T>(nibName: String?) -> T where T : UIView {
let bundle = Bundle(for: T.self)
let name = nibName ?? String(describing: T.self)
return bundle.loadNibNamed(name, owner: nil, options: nil)?.first as? T ?? T()
}
return fromNibHelper(nibName: nibName)
}
}
可以像这样使用：
let someView = SomeView.fromNib()
或者像这样：
let someView = SomeView.fromNib("SomeOtherNibFileName")