Introduction
Block KVO is a lightweight and easy-to-use library that allows you to observe changes in properties using blocks in Objective-C.
Features
- Simple and intuitive syntax
- Support for observing multiple properties
- Prevents memory leaks by automatically removing observers
- Compatible with iOS and macOS
Requirements
- iOS 10.0+ / macOS 10.12+
- Xcode 10.0+
Installation
CocoaPods
To integrate Block KVO into your Xcode project using CocoaPods, specify it in your Podfile
:
pod 'BlockKVO'
Then, run the following command:
$ pod install
Carthage
To integrate Block KVO into your Xcode project using Carthage, add the following line to your Cartfile
:
github "BlockKVO/BlockKVO"
Then, follow the Carthage documentation to integrate the framework.
Manual
- Download the latest release from the Block KVO repository.
- Drag and drop the
BlockKVO.framework
file into your Xcode project. - In the project settings, select your target and go to the General tab. Look for Frameworks, Libraries, and Embedded Content section, and make sure Embed & Sign is selected for
BlockKVO.framework
.
Usage
First, import the BlockKVO.h
header file:
#import <BlockKVO/BlockKVO.h>
Observing Changes
To observe changes in a property, use the following syntax:
[object block_observeKeyPath:@"propertyKey" options:NSKeyValueObservingOptionInitial | NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld block:^(id object, NSDictionary * _Nonnull change) {
// Handle property change
}];
The block is invoked whenever the property changes. The object
parameter is the object being observed, and the change
dictionary contains information about the change, such as the old and new values.
Removing Observers
Observers are automatically removed when the observed object is deallocated. However, if you want to remove an observer explicitly, use:
[object block_removeAllObservers];
Example
Here’s a simple example demonstrating how to use Block KVO:
// MyClass.h
#import <Foundation/Foundation.h>
@interface MyClass : NSObject
@property (nonatomic) NSString *name;
@end
// MyClass.m
#import "MyClass.h"
#import <BlockKVO/BlockKVO.h>
@implementation MyClass
- (instancetype)init {
self = [super init];
if (self) {
[self block_observeKeyPath:@"name" options:NSKeyValueObservingOptionInitial | NSKeyValueObservingOptionNew block:^(id object, NSDictionary * _Nonnull change) {
NSString *oldName = change[NSKeyValueChangeOldKey];
NSString *newName = change[NSKeyValueChangeNewKey];
NSLog(@"Name changed from %@ to %@", oldName, newName);
}];
}
return self;
}
@end
Conclusion
Block KVO simplifies observing changes in properties using blocks, saving you time and effort. Enjoy using this lightweight and powerful library in your Objective-C projects!