UIView setNeedsDisplay不起作用

Question

Simple code is here:

Custom MyButton.h

@interface PaiLifeReadingListButton : UIButton
@property (strong, nonatomic) UIImageView *logoImageView;
@end

Custom MyButton.m

@implementation PaiLifeReadingListButton
@synthesize logoImageView = _logoImageView;
-(id)init
{
    _logoImageView = [[UIImageView alloc] initWithFrame:CGRectMake(33.0, 20.0, 80.0, 80.0)];
    [_logoImageView setImage:[UIImage imageNamed:@"pic"]];
    [self addSubview: _logoImageView];
}  
@end

Custom MyView.h:

@property (strong, nonatomic) Mybutton *mybutton;

Custom MyView.m:

-(id) init
{
    myButton = [[MyButton alloc] init];
    [self addSubview:myButton];
}

ViewController.m:

@synthesize myView;
- (void)viewDidLoad
{
    myView = [[Myview alloc] init];
    [myView.myButton addTarget:self action:@selector(pressed:) forControlEvents:UIControlEventTouchDown];
    self.view = myView;
}
-(void)pressed : (MyButton *)button
{
    UIImageView *newImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"other-pic"] highlightedImage:nil];
    myView.myButton.logImageView = newImageView;
    [self.view setNeedsDisplay]; //----this does not work
}

When I press the button, the imageview does not change. How can I fix this? Thank you very much!

Answer 1

First thing , you don't need setNeedsDisplay here. setNeedsDisplay is used for redrawing the view (it internally calls the drawRect: method of the view if required) which is not what you want.

Second, you have given the class of your button as MyButton ,but in the actual .h and .m files, it is given as @interface PaiLifeReadingListButton and @implementation PaiLifeReadingListButton respectively.

Another thing, the view and button is not initialized with a frame. But I assume you have done that already, since your only problem is the image view not changing.

Answer 2

In your code in pressed method you should change views in the hierarchy, but you change only the object member. You can do something like

myView.myButton.logImageView.image = [UIImage imageNamed:@"other-pic"];