why is - (null) at the end of my object - objective-c

Question

I have the following class
#import <UIKit/UIKit.h>
#interface UIImageViewInfo : UIImageView
#property(nonatomic,strong) NSString* colorInfo;
#end
when creating an UIImageViewInfo in function1(post below) I get the correct result
"UIImageViewInfo: 0x1d8acd60; baseClass = UIImageView; frame = (0 0;
20 20); opaque = NO; userInteractionEnabled = NO; tag = 2000; layer =
CALayer: 0x1d8a0560>>"
but creating the something in function2(posted below) I get the -(null)
UIImageViewInfo: 0x8372c40; baseClass = UIImageView; frame = (0 0; 20
20); alpha = 0; hidden = YES; opaque = NO; userInteractionEnabled =
NO; tag = 2000; layer = CALayer: 0x8380090>> - (null)
Why is there a - (null) ??
Thanx in advance
P.S> here is more from my code
-(void)function1{
UIImageViewInfo *image;
self.solutionPinSlots = [[NSMutableArray alloc] init];
for (int i=0; i<M; i++) {
image = [[UIImageViewInfo alloc] initWithImage:[UIImage imageNamed:#"solutionPeg#2x.png"]];
image.translatesAutoresizingMaskIntoConstraints=NO;
image.hidden=YES;
image.alpha = 0;
image.colorInfo = #"clear";
image.tag = 2000*(self.brainController.slotsIndex+1) +i;
[self.solutionPinSlots addObject:image];
[self.view addSubview:(UIImageViewInfo *)self.solutionPinSlots[i]];
}
NSLog(#"solutionSlots: %#",self.solutionPinSlots);
__block int counter = 0;
[self.brainController.solution enumerateObjectsUsingBlock:^(NSString *peg, NSUInteger idx, BOOL *stop){
for (int i=0;i<M;i++) {
if ([self.brainController.slots[self.brainController.slotsIndex][i] isEqual:peg]) {
if (i==idx) {
((UIImageViewInfo *) self.solutionPinSlots[counter]).backgroundColor = [UIColor whiteColor];
((UIImageViewInfo *) self.solutionPinSlots[counter]).colorInfo=#"white";
}else{
((UIImageViewInfo *) self.solutionPinSlots[counter]).backgroundColor = [UIColor blackColor];
((UIImageViewInfo *) self.solutionPinSlots[counter]).colorInfo=#"black";}
((UIImageViewInfo *) self.solutionPinSlots[counter]).hidden=NO;
((UIImageViewInfo *) self.solutionPinSlots[counter++]).alpha=1;
}
}
}];
[self.solutionPinSlots shuffle];
[self updateSolutionPinSlots];
}
-(void)function2{
NSString *obj;
for (int idx=0; idx< M;idx++ ) {
UIImageViewInfo *image = [[UIImageViewInfo alloc] initWithImage:[UIImage imageNamed:#"solutionPeg#2x.png"]];
image.translatesAutoresizingMaskIntoConstraints=NO;
obj = (NSString *) [self.solutionPinSlots objectAtIndex:idx];
image.tag=2000*(self.brainController.slotsIndex+1)+idx;
image.hidden=NO;
image.alpha = 1;
if ([obj isEqualToString:#"clear"]) {
image.hidden=YES;
image.alpha = 0;
image.colorInfo=#"clear";
image.backgroundColor=[UIColor clearColor];
}else if ([obj isEqualToString:#"white"]){
image.colorInfo=#"white";
image.backgroundColor=[UIColor whiteColor];
}else if ([obj isEqualToString:#"black"]){
image.colorInfo=#"black";
image.backgroundColor=[UIColor blackColor];
}else{
NSLog(#"Something is Wrong!!!");
}
[self.solutionPinSlots replaceObjectAtIndex:idx withObject:image];
[self.view addSubview:image];
}
}

Answer 1

Never mind. It is coming from the description method of UIView, which is rather complex and dumps a bunch of information about the view. One of the conditionals is being tripped up by your configuration and causing the (null) at the end.
Safe to ignore.
There is no UIImageViewInfo class in UIKit, so the implementation must be in your project. In that implementation, there is likely a description method that is implemented something like:
- (NSString*)description {
....
return [NSString stringWithFormat:#"UIImageViewInfo:%p; %# - %#", self, [super description], someInstanceVariableThatHappensToBeNil]];
}
Only your description is likely more complex due to the sometimes does this sometimes that output.
Not that you should not prefix classes with UI when subclassing the UIKit.

Answer 2

It is because your NSLog call (which you do not show) is asking for a second object, and that second object is null.