U.S. President Barack Obama arrived in South Africa on Friday for the second leg of a trip overshadowed by the deteriorating health of anti-apartheid icon Nelson Mandela . Obama did not appear to rule out a visit to see the ailing former president , but said he will leave it up to the family . `` We 'll see what the situation is when we land , '' he said en route to Johannesburg . `` I do n't need a photo op , and the last thing I want to do is to be in any way obtrusive at a time when the family is concerned with Nelson Mandela 's condition . '' The president left the United States on Wednesday for Senegal , South Africa and Tanzania -- his second visit to sub-Saharan Africa since taking office . The trip aims to bolster African investment opportunities for U.S. businesses , address development issues such as food security and health , and promote democracy . It comes as China aggressively engages the continent , pouring billions of dollars into it and replacing the United States as Africa 's largest trading partner . Obama heads to Africa to promote investment , democracy . During his last day in Dakar , Senegal , Obama attended a food security session , where he met with farmers and innovators whose technologies are bolstering the lives of regional farmers . `` I know that millet and maize and fertilizer does n't always make for sexy copy , but ... I think if the American people knew the kind of work that is being done as a consequence of their generosity and their efforts , I think they would be very proud , '' he said . The event in the Senegalese capital Friday was his last before he jetted off to South Africa . Mandela 's condition . Mandela is clinging to life at a hospital in Pretoria , an issue weighing heavily in the continent , where he retains massive popularity despite his retirement from public life . His condition has improved , but his health remains delicate , said his ex-wife , Winnie Madikizela-Mandela . `` I can say that from what he was a few days ago , there is great improvement , but clinically he is still unwell , '' she told reporters . Mandela became an international figure while enduring 27 years in prison for fighting apartheid , South Africa 's system of racial segregation . He was elected the nation 's first black president in 1994 , four years after he was freed . Even as he has faded from the spotlight , he remains popular worldwide . Mandela , the U.S. president said , is a hero to him and many others . `` If and when he passes from this place , one thing I think we 'll all know is that his legacy is one that will linger on throughout the ages , '' Obama said . He said he had read Mandela 's writings and speeches , and understood `` that this was somebody who believed in that basic principle I just talked about -- treating people equally -- and was willing to sacrifice his life for that belief . '' Obama 's visit to South Africa will include a stop at Robben Island , where Mandela spent a majority of his decades in prison . The White House schedule does not include a visit with the anti-apartheid icon . Senegal visit . During a news conference Thursday in Dakar , Obama called on countries worldwide to decriminalize homosexuality , a day after the U.S. Supreme Court handed a major victory to proponents of same-sex marriage by striking down a key part of the Defense of Marriage Act . Every group of people has a right to its own views , Obama said . `` But when it comes to how the state treats people -- how the law treats people -- I believe that everybody has to be treated equal , '' he said . The remarks came in response to a question from CNN 's Jessica Yellin on whether Obama was pressing his Senegalese counterpart on the issue . Homosexuality is illegal in Senegal . `` Senegal is a very tolerant country which does not discriminate in terms of inalienable rights of human beings , '' Senegalese President Macky Sall said . `` People are not refused jobs for being gay , '' he said . `` But we are still not ready to decriminalize homosexuality . '' In Senegal , Obama also visited Goree Island , which once served as a strategic post in the transatlantic slave trade . Obama will spend the weekend in South Africa and then head to Tanzania , his last stop before returning to Washington next week . See also : Obama 's goal in Africa : Counter China .
Obama says visiting Mandela will depend on the family 's wishes . Comment: Mandela is a hero to many , the U.S. president says . Obama 's visit will include a stop at Robben Island , where Mandela spent time in prison .