@interface myTree : NSObject

@property (nonatomic,assign) NSInteger value;
@property (nonatomic,strong) myTree *leftMyTree;
@property (nonatomic,strong) myTree *rightMyTree;


+(myTree *)createTreeWithValue:(NSArray *)values;
@end

1. 暴露一个方法，创建一个树。

+ (myTree *)createTreeWithValue:(NSArray *)values{
    
    myTree *rootTree = nil;
    for (int i = 0; i<values.count; i++) {
        NSInteger value = [(NSNumber *) [values objectAtIndex:i] integerValue];
        rootTree = [myTree addTreeNode:rootTree value:value];
    }
    return rootTree;
}

遍历外界数组，

+ (myTree *)addTreeNode:(myTree *)treeNode value:(NSInteger)value {
    
    if (!treeNode) {
        return  nil;
    }
    //值小于根节点，则插入到左子树
    else if (value <= treeNode.value){
        treeNode.leftMyTree = [myTree addTreeNode:treeNode.leftMyTree value:value];
    }
    //值大于根节点，则插入到右子树
    else if (value >= treeNode.value){
        treeNode.rightMyTree = [myTree addTreeNode:treeNode.rightMyTree value:value];
    }
    
    return treeNode;
}

递归调用 addTreeNode：value： 方法创建二叉树。
水平有限，不足之处，还望指正。