加载 UIView 子类的 Nib 的正确方法

MyViewClass *myViewObject = [[[NSBundle mainBundle] loadNibNamed:@"MyViewClassNib" owner:self options:nil] objectAtIndex:0]

I'm using this to initialise the reusable custom views I have.

Note that you can use "firstObject" at the end there, it's a little cleaner. "firstObject" is a handy method for NSArray and NSMutableArray.

Here's a typical example, of loading a xib to use as a table header. In your file YourClass.m

- (UIView *)tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section {
return [[NSBundle mainBundle] loadNibNamed:@"TopArea" owner:self options:nil].firstObject;
}

Normally, in the TopArea.xib, you would click on File Owner and set the file owner to YourClass. Then actually in YourClass.h you would have IBOutlet properties. In TopArea.xib, you can drag controls to those outlets.

Don't forget that in TopArea.xib, you may have to click on the View itself and drag that to some outlet, so you have control of it, if necessary. (A very worthwhile tip is that when you are doing this for table cell rows, you absolutely have to do that - you have to connect the view itself to the relevant property in your code.)

Follow the following steps

1. Create a class named MyView .h/.m of type UIView.
2. Create a xib of same name MyView.xib.
3. Now change the File Owner class to UIViewController from NSObject in xib. See the image below

4. Connect the File Owner View to your View. See the image below

5. Change the class of your View to MyView. Same as 3.

6. Place controls create IBOutlets.

Here is the code to load the View:

UIViewController *controller=[[UIViewController alloc] initWithNibName:@"MyView" bundle:nil];
MyView* view=(MyView*)controller.view;
[self.view addSubview:myview];

Hope it helps.

Clarification:

UIViewController is used to load your xib and the View which the UIViewController has is actually MyView which you have assigned in the MyView xib..

Demo I have made a demo grab here

Well you could either initialize the xib using a view controller and use viewController.view. or do it the way you did it. Only making a UIView subclass as the controller for UIView is a bad idea.

If you don't have any outlets from your custom view then you can directly use a UIViewController class to initialize it.

Update: In your case:

UIViewController *genericViewCon = [[UIViewController alloc] initWithNibName:@"CustomView"];
//Assuming you have a reference for the activity indicator in your custom view class
CustomView *myView = (CustomView *)genericViewCon.view;
[parentView addSubview:myView];
//And when necessary
[myView.activityIndicator startAnimating]; //or stop

Otherwise you have to make a custom UIViewController(to make it as the file's owner so that the outlets are properly wired up).

YourCustomController *yCustCon = [[YourCustomController alloc] initWithNibName:@"YourXibName"].

Wherever you want to add the view you can use.

[parentView addSubview:yCustCon.view];

However passing the another view controller(already being used for another view) as the owner while loading the xib is not a good idea as the view property of the controller will be changed and when you want to access the original view, you won't have a reference to it.

EDIT: You will face this problem if you have setup your new xib with file's owner as the same main UIViewController class and tied the view property to the new xib view.

i.e;

• YourMainViewController -- manages -- mainView
• CustomView -- needs to load from xib as and when required.

The below code will cause confusion later on, if you write it inside view did load of YourMainViewController. That is because self.view from this point on will refer to your customview

-(void)viewDidLoad:(){
UIView *childView= [[[NSBundle mainBundle] loadNibNamed:@"YourXibName" owner:self options:nil] objectAtIndex:0];
}

If you want to keep your CustomView and its xib independent of File's Owner, then follow these steps

• Leave the File's Owner field empty.
• Click on actual view in xib file of your CustomView and set its Custom Class as CustomView (name of your custom view class)
• Add IBOutlet in .h file of your custom view.
• In .xib file of your custom view, click on view and go in Connection Inspector. Here you will all your IBOutlets which you define in .h file
• Connect them with their respective view.

in .m file of your CustomView class, override the init method as follow

-(CustomView *) init{
CustomView *result = nil;
NSArray* elements = [[NSBundle mainBundle] loadNibNamed: NSStringFromClass([self class]) owner:self options: nil];
for (id anObject in elements)
{
if ([anObject isKindOfClass:[self class]])
{
result = anObject;
break;
}
}
return result;
}

Now when you want to load your CustomView, use the following line of code [[CustomView alloc] init];

Answering my own question about 2 or something years later here but...

It uses a protocol extension so you can do it without any extra code for all classes.

/*


Prerequisites
-------------
- In IB set the view's class to the type hook up any IBOutlets
- In IB ensure the file's owner is blank


*/


public protocol CreatedFromNib {
static func createFromNib() -> Self?
static func nibName() -> String?
}


extension UIView: CreatedFromNib { }


public extension CreatedFromNib where Self: UIView {


public static func createFromNib() -> Self? {
guard let nibName = nibName() else { return nil }
guard let view = NSBundle.mainBundle().loadNibNamed(nibName, owner: nil, options: nil).last as? Self else { return nil }
return view
}


public static func nibName() -> String? {
guard let n = NSStringFromClass(Self.self).componentsSeparatedByString(".").last else { return nil }
return n
}
}


// Usage:
let myView = MyView().createFromNib()

In Swift:

For example, name of your custom class is InfoView

At first, you create files InfoView.xib and InfoView.swiftlike this:

import Foundation
import UIKit


class InfoView: UIView {
class func instanceFromNib() -> UIView {
return UINib(nibName: "InfoView", bundle: nil).instantiateWithOwner(nil, options: nil)[0] as! UIView
}

Then set File's Owner to UIViewController like this:

Rename your View to InfoView:

Right-click to File's Owner and connect your view field with your InfoView:

Make sure that class name is InfoView:

And after this you can add the action to button in your custom class without any problem:

And usage of this custom class in your MainViewController:

func someMethod() {
var v = InfoView.instanceFromNib()
v.frame = self.view.bounds
self.view.addSubview(v)
}