How did the Pahlavi regime and the Islamic Republic reacted with apartheid?

A simple and clear comparison:

Apartheid regime in South Africa in 1948 ruled upon the destiny of Africans. And promoted reactions by choosing racist and discriminatory policies against the indigenous black African public. Apart from the internal struggles that brought many African freedom fighters in to the stage, the international community also reacted to boycott the apartheid government. Except a handful of states, political and economic relations with the said government decreased.
To deal with this political isolation, the apartheid regime decided to adopt certain policies. One of these was the role against Soviet communism. This approach made a close relationship between west and African apartheid government and till the fall of the regime, main support came from the countries of Western white.
Pahlavi government`s relation and South Africa was in high level, and Iran was the most important oil supplier to South Africa. Despite the mandatory UN sanctions, Iran`s oil exports continued until the fall of the Shah. While after the revolution in 1980, only a small country of Brunei remained to export oil to South Africa.
South Africa during the World Economic sanctions, began a program for coal fuel and converting the coal to oil. National Iranian Oil Company in 1967 made a contract to export seventy percent of the oil needed by south African government, equal to 000/035/25 metric tons of crude oil for 15 years to NATROF refinery, instead south Africa exports uranium and steel to Iran.
Violence and racial segregation of apartheid regime in South Africa, provoked opposition from many countries in the world
South African government, before antiapartheid movements and review of the basic policies led the country, only had 43 embassies in the countries, including the white nations of Western Europe, Pahlavi Iran and the Israeli. After OPEC embargo in 1973 until the fall of the Pahlavi regime, Iran was organizing, more than ninety percent oil import of South Africa and instead, iron ore, steel, cement, corn, sugar and other agricultural products were imported.
Iran as Gendarme of the Persian Gulf on behalf of the West in the geopolitical region and South Africa's role as an agent of the West to fight the spread of communist activities, the convergence of the two countries to avoid the influence of the Soviet Union and the communist system and need of the apartheid regime, to Iran's Oil expanded relations between Iran and South Africa.
The two governments, because of the sanctions could have higher level relations, but they were able to establish consulates in the countries. The first South African consulate was established in mid-1970 in Tehran, and Iran on 30 November of the same year opened a consulate in Johannesburg.
Economic activities of the two countries before the revolution, was only in petroleum activities. SASOULBERG refinery contracts (NATROF) and oil sales contracts as long term were more important than other agreements.
In the year 1974-75, Iranian government supplied 78 per cent of south Africa`s oil need, in 1977-78, 90% and in 1978, one year before the revolution, 98%. Following the 3379 UN resolution against racism, in the Middle East, Iran did not comply with this resolution and continued its relationship with South Africa till fall of Shah.
The forefront countries protested the Iran's cooperation with South Africa and the President of Zambia, Kenneth KONDA wanted to go to Iran and talk with Iranian officials but Pahlavi government authorities, rejected the proposal.
Mohammad Reza Pahlavi`s government, because of ideological reasons, along with economical interest and following the policies of the West, did not want to cut ties with south Africa or boycott it.
Before the revolution, following Tehran and Johannesburg mayors trips, to these cities in 1974, they signed a sister agreement between the two cities and a street of Johannesburg, was named as Tehran. And also, one of the theaters and streets of Durban, was called Shiraz. During the Pahlavi regime in Iran, the relation of Iran and South Africa, despite the general prohibitions and sanctions of international organizations, the Pahlavi dynasty`s interest and ideological harmony and also some Economical benefits was good. The Pahlavi people could not increase their relation, from the level of consulate, because of some apparent necessities.
By victory of Islamic Revolution in Iran led by Imam Khomeini, changes were inverted. The system derived from the Islamic Revolution, was against apartheid and racism. And its principles were to support the liberation movements of the oppressed people. The idea of cutting ties with the racist South African government introduced even before the revolution. Imam Khomeini in NEAUPHLE-LE-CHATEAU about oil sales to South Africa and Israel declared:
"We are not willing to sell oil to racist country and murderous and enemies of humanity." Elsewhere he says, "... if South Africa does not end this situation, we can`t establish a relationship with them and will not give oil.

Imam Khomeini, before revolution, was promising about

breaking tie with the apartheid government
Ties were cut by the end of 1979. The Islamic Republic of Iran suspended the oil cooperation with regime of apartheid government. The oil embargo had great economic impact on South Africa government. The interim government, in the beginning of works has approved the import and export of the products to Israel and South Africa, as well as export of Iran are illegal. After the relation break, in 1980, the Swiss government was determined as supporter of benefits for both the countries.
Islamic Republic of Iran, beside cut ties with the apartheid government, contacted liberal activist groups, and with various titles, supported their campaigns. An office for Namibia's liberation movement (SWAPO) was opened in Tehran. And support for the struggle of the African National Congress was considered. After the release of Nelson Mandela and his meeting with Ayatollah Khamenei, was natural outcome of this relationship.
Active participation in international sanctions against South Africa, issuing a statement by the foreign ministry in relation to African problems, and participating in antiapartheid conferences, were the supports of the Islamic Republic. During tie-up, relations were made with Muslims of this country and for different programs and meetings, they were invited to Iran.

The Islamic Republic of Iran since the overthrow of apartheid regim

began a warm relations with the new government
Along with the intensification of internal conflicts, external pressure against the apartheid regime excessed. The pressure was so much that even Margaret Thatcher, the British prime minister, who had always disagreed about sanctions against South African government, was forced to remain silent. Following four years of intensive discussions from 1990 to 1994 between the apartheid government and the ANC (the group which was in charge of campaign),
Transitional Executive Council bill that allowed blacks to participate in government decisions after 300 years of white decision-making monopoly, was approved by the party leaders. Following this approval, the African National Congress leader Nelson Mandela during a speech requested for an end to global restrictions against South Africa. With conducting the first elections in Africa, Mandela became first black president and relations with all countries were resumed.
Islamic republic government of Iran in response to Mandela and congress ended the economic and trade sanctions against South Africa ended in 1993, and preparations were made for the development of relations between the two countries.