Set the current Value of UITextField to a property when UITextField's "editingDidBegin" control event fire

Question

How to set the current value of UITextField to a property(through a custom setter) declared in category which extends UITextField class when firing editingDidBegin control event of UITextField?

Answer 1

You should be able to do this using a category by taking advantage of Associative References.

From the docs:

Using associative references, you can add storage to an object without modifying the class declaration.

Here's an example that will get you going in the right direction:

.h file:

@interface UITextField (StoredProperty)

@property (nonatomic, strong) NSString *testString;

@end

.m file:

#import <objc/runtime.h>

static void *MyStoredPropertyKey = &MyStoredPropertyKey;

@implementation UITextField (StoredProperty)

- (NSString *)testString {
    return objc_getAssociatedObject(self, MyStoredPropertyKey);
}

- (void)setTestString:(NSString *)testString {
    objc_setAssociatedObject(self, MyStoredPropertyKey, testString, OBJC_ASSOCIATION_RETAIN_NONATOMIC); 
}

@end

Example use:

NSObject *obj = [NSObject new];
obj.testString = @"This is my test string";
NSLog(@"%@", obj.testString);