Insertion and deletion into a binary search tree in objective c

gistfile1.m

#import 
 
@interface Node : NSObject{
    Node *left;
    Node *right;
    NSObject *data;
}
 
@property (nonatomic, strong) Node *left;
@property (nonatomic, strong) Node *right;
@property (nonatomic, strong) NSObject *data;
@end
 
#import "Node.h"
 
@implementation Node
@synthesize left;
@synthesize right;
@synthesize data;
@end
 
-(Node*) insertNode:(Node*) root forObject:(NSObject*)data{
     
    Node *cur = root;
    Node *prev = NULL, *temp;
     
    temp = [[Node alloc] init];
    temp.data = data;
    temp.left = temp.right = NULL;
     
    if(root == NULL){
        root = temp;
    }else{
         
        // iterate through the nodes
        NSString *valStr = (NSString*) data;
        NSInteger val  = [valStr intValue];
        while (cur != NULL) {
            prev = cur;
            NSString *valStr2 = (NSString*) cur.data;
            cur = (val < [valStr2 intValue]) ? cur.left: cur.right;
        }
        NSString *valStr2 = (NSString*)prev.data;
        if(val < [valStr2 intValue]){
            prev.left = temp;
        }else{
            prev.right = temp;
        }
    }
    return root;
}
 
-(Node*) deleteNode:(Node*) root forValue:(NSObject*) value{
     
    if (root == NULL) {
        return root;
    }
     
    Node *curr = root;
    Node *parent;
    int val = [(NSString*)value intValue];
    while (curr != NULL && val != [(NSString*)curr.data intValue]) {
        parent = curr;
        curr = (val < [(NSString*)curr.data intValue])  ? curr.left : curr.right;
    }
     
    if (curr == NULL) {
        NSLog(@"item not found");
        return root;
    }
     
    Node *q, *suc;
    if (curr.left == NULL) {
        q = curr.right;
    }else if (curr.right == NULL){
        q = curr.left;
    }else{
        // obtain in order successor
        suc = curr.right;
        while (suc.left != NULL) {
            suc = suc.left;
        }
        suc.left = curr.left;
        q = curr.right;
    }
     
    if (parent == NULL) {
        return q;
    }
    if (curr == parent.left) {
        parent.left = q;
    }else{
        parent.right = q;
    }
    curr = NULL;
    return root;
}
 
-(void) displayInorder:(Node*)root{
    if(root != NULL){
        [self displayInorder:root.left];
        NSLog(@"%@ ", root.data);
        [self displayInorder:root.right];
    }
}
 
// from your main program
- (void) main
{
    [super viewDidLoad];
     
    Node *root = NULL;
    NSArray *array = [[NSArray alloc] initWithObjects:@"100",@"1", @"99", @"23", @"13", nil];
    for (NSObject *val in array) {
        root = [self insertNode:root forObject:val];
    }
    [self deleteNode:root forValue:@"23"];
    [self displayInorder:root];
    return;