I'm following along with Apple's "Hello" tutorial on iOS, and I'd like to know why it's necessary to declare the "userName" variable (to be accessed in code later). Isn't it generated by the synthesize statement?
#interface HelloWorldViewController : UIViewController {
NSString *userName;
}
- (IBAction)changeGreeting:(id)sender;
#property (weak, nonatomic) IBOutlet UILabel *label;
#property (weak, nonatomic) IBOutlet UITextField *testField;
#property (nonatomic, copy) NSString *userName;
And here's the implementation of synthesize:
#synthesize label=_label;
#synthesize testField=_testField;
#synthesize userName=_userName;
It wasn't always generated by the property/synthesize. That's a relatively new addition to Objective-C. The tutorial was probably written before this was the case.
Related
I have a view controller HomeController & BookController.I am going from view controller HomeController to BookController.I am passing data back to previous view controller.So i have used this approach.
#import <UIKit/UIKit.h>
#import "BaseController.h"
#import <MediaPlayer/MediaPlayer.h>
#protocol HomeProtocol
- (void)setComment:(BOOL)data;
-(void)setCommnetArray:(NSMutableArray*)data;
#end
#protocol BookProtocol
-(void)setBook:(BOOL)status;
#end
#interface HomeViewController : BaseController<UITableViewDataSource,UITableViewDelegate,HomeProtocol,UIScrollViewDelegate,BookProtocol,UINavigationControllerDelegate>
#property (weak, nonatomic) IBOutlet UITableView *table_view;
#property BOOL hasUserPostedComment;
#property NSInteger commentIndex;
#property (weak, nonatomic) IBOutlet UILabel *label_post_status;
#property UIRefreshControl *refreshControl;
#property NSInteger start_offset;
#property NSInteger end_offset;
#property (weak, nonatomic) IBOutlet UIButton *btn_refresh;
#property NSMutableArray *temp_user_cooments;
#property MPMoviePlayerController *moviePlayerController;
#property BOOL isBookMarkLoaded;
#end
BookMarkController.h
#import <UIKit/UIKit.h>
#import "BaseController.h"
#import "HomeViewController.h"
#import <MediaPlayer/MediaPlayer.h>
#protocol HomeProtocol
- (void)setComment:(BOOL)data;
-(void)setCommnetArray:(NSMutableArray*)data;
#end
#interface BookMarkController : BaseController<UITableViewDataSource,UITableViewDelegate,HomeProtocol,UIScrollViewDelegate>
#property (nonatomic, weak) id<BookProtocol> myDelegate;
#property (weak, nonatomic) IBOutlet UITableView *table_view;
#property BOOL hasUserPostedComment;
#property NSInteger commentIndex;
#property (weak, nonatomic) IBOutlet UILabel *label_post_status;
#property UIRefreshControl *refreshControl;
#property NSInteger start_offset;
#property NSInteger end_offset;
#property (weak, nonatomic) IBOutlet UIButton *btn_refresh;
#property NSMutableArray *temp_user_cooments;
#property MPMoviePlayerController *moviePlayerController;
#property NSString *index;
#end
Method implementation
-(void)setBook
{
NSLog(#"set book called");
self.isBookMarkLoaded=true;
}
It gives error Unrecognized selector sent to instance.Please tell me what is the issue here.
#protocol BookProtocol
-(void)setBook:(BOOL)status;
#end
Add above protocol to BookMarkController.h. Create delegate of the same in BookMarkController.h file. Make a call to -(void)setBook:(BOOL)status; from BookMarkController.m file
Add delegate in HomeViewController.h file. Define -(void)setBook:(BOOL)status; in HomeViewController.m file and also assign delegate to self.
That's all.
What made the difference
#property (strong, nonatomic) and #property (nonatomic, strong) in ios.
i will define iboutlet for example uilabel like this
#property (strong, nonatomic) IBOutlet UILabel *label1;
and i see many time in this site
#property (nonatomic, strong) NSString* str;
What is the difference between the two property.
There are no differences in the logic. They represent the same thing but with different order.
Usually in IBOutlets you have #property (weak, nonatomic) because it is auto generated when you ctrl+drag from interface builder.
However, most people prefer the second form because the "nonatomic" is used in most of the cases in ios and therefore it is easily ignored.
There is no difference. But in apple sample codes and most frequently we use :
#property (nonatomic, strong)
From my MCSettingsFormViewController, I want to set MatchCenterViewController's didAddNewItem BOOL property, but without making use of a segue.
I've imported MatchCenterViewController.h, which contains that property like so:
#property (assign) BOOL didAddNewItem;
However, when I try to set it like this: MatchCenterViewController.didAddNewItem = YES;, it says "property didAddNewItem not found on object of type 'MatchCenterViewController'".
I assume this is because I haven't defined what MatchCenterViewController is. If so, how can I do this property so it sets the property correctly?
edit:
MatchCenterViewController.h:
#import <UIKit/UIKit.h>
#import <Parse/Parse.h>
#import "AsyncImageView.h"
#import "SearchViewController.h"
#import "WebViewController.h"
#import "WSCoachMarksView.h"
#import "SLExpandableTableView.h"
#interface MatchCenterViewController : UIViewController <UITableViewDataSource>
#property (strong, nonatomic) NSString *itemSearch;
#property (strong, nonatomic) NSString *itemPriority;
//#property (strong, nonatomic) IBOutlet UITextField *itemSearch;
#property (nonatomic, strong) NSArray *imageURLs;
#property (strong, nonatomic) NSString *matchingCategoryCondition;
#property (strong, nonatomic) NSString *matchingCategoryLocation;
#property (strong, nonatomic) NSNumber *matchingCategoryMaxPrice;
#property (strong, nonatomic) NSNumber *matchingCategoryMinPrice;
#property (strong, nonatomic) NSNumber *matchingCategoryId;
#property (strong, nonatomic) NSArray *matchCenterArray;
#property (strong, nonatomic) NSString *searchTerm;
#property (strong, nonatomic) NSString *itemURL;
#property (assign) NSInteger expandedSection;
#property (assign) NSInteger rowCount;
#property (assign) BOOL didAddNewItem;
#property (assign) BOOL results;
#property (strong, nonatomic) IBOutlet UIButton *editButton;
#property (weak, nonatomic) IBOutlet UIButton *moreButton;
#property (strong) NSMutableSet *expandedSections;
#end
#interface MoreButton : UIButton
#property (assign) NSInteger expandedSection;
#property (assign) NSInteger sectionIndex;
#end
MCSettingsFormViewController.h:
#import <UIKit/UIKit.h>
#import <QuartzCore/QuartzCore.h>
#import <Parse/Parse.h>
#import "MatchCenterViewController.h"
#interface MCSettingsFormViewController : UIViewController
#property (strong, nonatomic) NSString *minPrice;
#property (strong, nonatomic) NSString *maxPrice;
#property (strong, nonatomic) NSString *itemCondition;
#property (strong, nonatomic) NSString *itemLocation;
#property (strong, nonatomic) NSString *searchTerm;
#property (strong, nonatomic) NSString *itemPriority;
#property (strong, nonatomic) IBOutlet UITextField *tf;
#property (strong, nonatomic) IBOutlet UITextField *tf1;
#property (strong, nonatomic) IBOutlet UITextField *tf2;
#end
You need to use an instance of MatchCenterViewController not the name of the class. Presumably, somewhere in your app there's a reference to a MatchCenterViewController object. You can either access that reference or pick a different way of letting it know about the change.
For example, if your two controllers aren't connected to each other, you could post a notification in MCSettingsFormViewController and react to it in MatchCenterViewController.
For more specific suggestions, I'd need to know how both controllers are created and presented.
When you instantiate MatchCenterViewController, you could set it as a delegate of MCSettingsFormViewController. That way, the MatchCenterViewController defines itself as the instantiated version of the class to be edited by the MatchCenterViewController.
Here is a basic tutorial for delegates: http://www.tutorialspoint.com/ios/ios_delegates.htm
So based off of your headers, it looks like either your MCSettingsFormViewController doesn't have a property of type MatchCenterViewController-- or that property is private.
In the former case, you need to add a property to your MCSettingsFormViewController with type MatchCenterViewController.
In the latter you aren't initializing your MatchCenterViewController property.
So first, make sure you have that public/private property.
Then, when you first create and show your SettingsFormViewController, set this property to your MatchCenterViewController instance. Now your SettingsForm has a reference to the proper instance you're looking for.
At this point, you can set the property on the MatchCenter
I want to add my custom NSObject class to other as property, is that possible?
Class look like this:
#interface PlaceHolder : NSObject
#property (strong, nonatomic) NSString *name;
#property (strong, nonatomic) NSString *description;
#property (strong, nonatomic) NSString *webPage;
I want to make it property of my other class to initialize it once, and then work with properties - name, description. webpage and other..
Do i need to create a category? Or there is another way to achieve this?
Any advice would be appreciated, thank you.
Just add a property to the class that needs to use it
#property (strong, nonatomic) PlaceHolder *placeHolder;
I declare my .h file like this:
#import <UIKit/UIKit.h>
#interface NavigationTripViewController : UIViewController <UIPickerViewDelegate, UIPickerViewDataSource>{
NSArray *questionTitleTrip;
NSArray *questionDescTrip;
NSMutableArray *answerTrip;
NSMutableArray *pickerChoices;
int questionInt;
int totalInt;
IBOutlet UILabel *questionNum;
IBOutlet UILabel *questionTotalNum;
IBOutlet UILabel *recordType;
IBOutlet UITextView *questionDes;
IBOutlet UIView *answerView;
IBOutlet UIButton *preButton;
IBOutlet UIButton *nextButton;
UITextField *text;
UIPickerView *picker;
}
#property (retain, nonatomic) NSArray *questionTitleTrip;
#property (retain, nonatomic) NSArray *questionDescTrip;
#property (retain, nonatomic) NSMutableArray *answerTrip;
#property (retain, nonatomic) NSMutableArray *pickerChoices;
#property (retain, nonatomic) IBOutlet UILabel *questionNum;
#property (retain, nonatomic) IBOutlet UILabel *questionTotalNum;
#property (retain, nonatomic) IBOutlet UILabel *recordType;
#property (retain, nonatomic) IBOutlet UITextView *questionDes;
#property (retain, nonatomic) IBOutlet UIView *answerView;
#property (retain, nonatomic) IBOutlet UIButton *preButton;
#property (retain, nonatomic) IBOutlet UIButton *nextButton;
#property (retain, nonatomic) UITextField *text;
#property (retain, nonatomic) UIPickerView *picker;
-(IBAction)clickPre;
-(IBAction)clickNext;
#end
And my .m file here like this:
#import "NavigationTripViewController.h"
#import <QuartzCore/QuartzCore.h>
#interface NavigationTripViewController ()
#end
#implementation NavigationTripViewController
#synthesize questionTitleTrip,questionDescTrip,answerTripl,pickerChoices,questionNum,questionTotalNum,recordType,questionDes,answerView,preButton,nextButton,text,picker;
All my variables in the #synthesize receive the warnings:
Autosynthesized property 'myVar' will use synthesized instance variable '_myVar', not existing instance variable 'myVar'
Also, the variables and class names used in viewDidLoad don't display in colors, just show in black color. In other view controllers, there are no warnings like this. How to fix these problems?
Edit:
Basically for all intents and purposes you should be building on a new enough XCode to use the new behavior, in that solution you typically will just remove the ivar from the #interface block in the .h file... If for some reason you do need to access an ivar directly you can now declare it in the #implementation block... and use #synthesize var or #synthesize var=_var
OGPost:
to make that go away you can go all new school and drop the iVar, or you can go all old school and add an #synthesize someIvar in your #implementation block.