How to obtain UITextFields from a singleton
I need just four parameters to drive the calculations in three view controllers. The parameters come from four UITextFields in the first view. I'm not using global variables but have developed a singleton class to enable the parameters to be available to each controller. I can reference the variables OK in the controllers but I don't know how to initialize them. I've obtained the variables from the first viewcontroller through a windows I developed with IB but can't seem to find a way to get these initialized in the singleton.
Help and guidance gratefully appreciated.
//
// GlobalParameters.h
// ProjectEstimator
//
// This 开发者_高级运维is a SINGLETON class used to handle global parameters for use in the various view controllers.
//
//
//
// Created by Frank Williamson on 10/06/2010.
//
#import <Foundation/Foundation.h>
@interface GlobalParameters : NSObject {
// Place any "global" variables here
// float *processes;
// float *entities;
// float *transactions;
// float *users;
IBOutlet UITextField *noOfProcesses;
IBOutlet UITextField *noOfEntityClusters;
IBOutlet UITextField *noOfTransactions;
IBOutlet UITextField *noOfUserArea;
}
@property (retain, nonatomic) UITextField *noOfProcesses;
@property (retain, nonatomic) UITextField *noOfEntityClusters;
@property (retain, nonatomic) UITextField *noOfTransactions;
@property (retain, nonatomic) UITextField *noOfUserArea;
// message from which our instance is obtained
+ (GlobalParameters *)sharedInstance;
@end
//
// GlobalParameters.m
// ProjectEstimator Singleton for handling (global) parameters.
//
// Created by Frank Williamson on 10/06/2010.
//
#import "GlobalParameters.h"
@implementation GlobalParameters;
@synthesize noOfProcesses;
@synthesize noOfEntityClusters;
@synthesize noOfTransactions;
@synthesize noOfUserArea;
+ (GlobalParameters *)sharedInstance{
// the instance of this class is stored here
static GlobalParameters *noOfProcesses = nil;
static GlobalParameters *noOfEntityClusters = nil;
static GlobalParameters *noOfTransactions = nil;
static GlobalParameters *noOfUserArea = nil;
// check to see if an instance already exists
if (nil == noOfProcesses) {
noOfProcesses = [[[self class] alloc] init];
// **How to I initialize UITextFields from a ViewController in here??**
}
// return the instance of this class
return noOfProcesses;
if (nil == noOfEntityClusters) {
noOfEntityClusters = [[[self class] alloc] init];
// **How to I initialize UITextFields from a ViewController in here??**
}
// return the instance of this class
return noOfEntityClusters;
if (nil == noOfTransactions) {
noOfTransactions = [[[self class] alloc] init];
// **How to I initialize UITextFields from a ViewController in here??**
}
// return the instance of this class
return noOfTransactions;
if (nil == noOfUserArea) {
noOfUserArea = [[[self class] alloc] init];
// **How to I initialize UITextFields from a ViewController in here??**
}
// return the instance of this class
return noOfUserArea;
}
@end
There's a number of things here I would change. First, I wouldn't create a "Globals" class. Second, if I did, would never store UIView
objects in class designed to be a "model". Third, if I absolutely needed to implement a singleton, I would follow the design pattern for Cocoa.
I need just four parameters to drive the calculations in three view controllers.
And at that point I recommend you throw out this class entirely and re-think your design problem. Is it simply that you need to store four NSString
parameters (or NSNumber
s or NSInteger
s or float
s or...)? If so, it's complete overkill to store the parameters inside a view class. Just create a simple class to store the parameters, whose header would look something like:
@interface MyParameters : NSObject
{
NSString* someString;
NSNumber* someNumber;
NSInteger someInteger;
float someFloat;
}
@property (nonatomic, retain) NSString* someString;
@property (nonatomic, retain) NSNumber* someNumber;
@property (nonatomic, assign) NSInteger someInteger;
@property (nonatomic, assign) float someFloat;
@end
I would instantiate an object of this class either in my application delegate or in my root view controller, and then I would pass it along to any other view controllers that needed access to it. Finally, I would use Key-Value Observing so every view controller that needs it will get automatic updates to any changes to the parameters.
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