Implementing a Custom View in Objective-C for User Selection and Text Input
In this article, we’ll explore how to create a custom view in Objective-C that allows users to select items from a list and input text on a UITextView. We’ll break down the implementation into smaller sections, providing explanations and code examples along the way.
Understanding the Requirements
The user wants to create a view that displays a list of users and allows them to select a specific user. Once a user is selected, they can input text in a UITextView similar to Facebook’s “What’s on your mind?” feature. The goal is to implement this custom view using Objective-C.
Project Setup
To begin, create a new Single View App project in Xcode. This will provide the basic structure for our app, including a navigation controller and a view hierarchy.
Designing the Custom View
Our custom view will consist of two main components: a UITableView for displaying user lists and a UITextView for text input. We’ll use a navigation controller to manage the stack of pushed view controllers.
Here’s an example code snippet that demonstrates the basic layout:
{
<highlight language="objectivec">
#import "CustomViewController.h"
@interface CustomViewController : UIViewController
@property (strong, nonatomic) UITableView *userTableView;
@property (strong, nonatomic) UITextView *textInputView;
@end
}
In the implementation file (CustomViewController.m), we’ll configure the view hierarchy:
{
<highlight language="objectivec">
#import "CustomViewController.h"
@implementation CustomViewController
- (instancetype)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Configure view hierarchy
self.userTableView = [[UITableView alloc] init];
self.textInView = [[UITextView alloc] init];
[self.view addSubview:self.userTableView];
[self.view addSubview:self.textInView];
// Add layout constraints and configure table view data source
}
return self;
}
@end
}
Implementing the UITableView Data Source
To display user lists, we’ll need to implement the UITableViewDataSource protocol. We’ll create a simple data model to store user information:
{
<highlight language="objectivec">
#import "CustomViewController.h"
@interface CustomUserData : NSObject
@property (strong, nonatomic) NSString *username;
@property (strong, nonatomic) NSString *profilePictureURL;
@end
}
In the CustomViewController implementation, we’ll create an array of CustomUserData objects to populate the table view:
{
<highlight language="objectivec">
#import "CustomViewController.h"
@implementation CustomViewController
- (void)viewDidLoad {
[super viewDidLoad];
// Create data source array
self.userDataSource = [[NSMutableArray alloc] initWithObjects:
[[CustomUserData alloc] initWithUsername:@"JohnDoe" profilePictureURL:@"https://example.com/johndoe.jpg"],
[[CustomUserData alloc] initWithUsername:@"JaneDoe" profilePictureURL:@"https://example.com/janedoe.jpg"]],
nil];
// Configure table view data source
self.userTableView.dataSource = self;
}
@end
}
We’ll also implement the tableView(_:numberOfRowsInSection:) method to return the number of rows in each section:
{
<highlight language="objectivec">
#import "CustomViewController.h"
@implementation CustomViewController
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
return self.userDataSource.count;
}
@end
}
Implementing the UITextView Delegate
To implement the text input feature, we’ll need to implement the UITextViewDelegate protocol. We’ll create a method to handle changes in the text view:
{
<highlight language="objectivec">
#import "CustomViewController.h"
@interface CustomViewController : UIViewController
// ...
@property (weak, nonatomic) id<UITextViewDelegate> textViewDelegate;
@end
}
In the implementation file (CustomViewController.m), we’ll implement the textView(_:shouldChangeTextInRange:replacementText:) method:
{
<highlight language="objectivec">
#import "CustomViewController.h"
@implementation CustomViewController
- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text {
// Check if text input has started
if ([text length] > 0 && ![text isEqualToString:@""]) {
// Change color of text view to black
textView.backgroundColor = [UIColor blackColor];
} else {
// Reset text view color to gray
textView.backgroundColor = [UIColor grayColor];
}
return YES;
}
@end
}
Implementing the Arrow Button Tapping
To push the ViewController with the table view, we’ll implement the arrow button tapping:
{
<highlight language="objectivec">
#import "CustomViewController.h"
@interface CustomViewController : UIViewController
// ...
@property (weak, nonatomic) ViewController *tableViewController;
@end
}
In the implementation file (CustomViewController.m), we’ll implement the buttonTapped: method:
{
<highlight language="objectivec">
#import "CustomViewController.h"
@implementation CustomViewController
- (void)buttonTapped:(id)sender {
// Push table view controller
self.tableViewController = [[ViewController alloc] init];
[self.navigationController pushViewController:self.tableViewController animated:YES];
}
@end
}
Conclusion
In this article, we’ve explored how to create a custom view in Objective-C that allows users to select items from a list and input text on a UITextView. We’ve broken down the implementation into smaller sections, providing explanations and code examples along the way.
By following these steps, you should be able to implement your own custom view for user selection and text input using Objective-C.
Last modified on 2024-08-10