if ([[UIApplication sharedApplication] canOpenURL:[NSURL URLWithString:@"Sinaweibo://"]]) {    // 新浪微博}if ([[UIApplication sharedApplication] canOpenURL:[NSURL URLWithString:@"weixin://"]]) {    // 微信}if ([[UIApplication sharedApplication] canOpenURL:[NSURL URLWithString:@"Facebook://"]]) {    // facebook}if ([[UIApplication sharedApplication] canOpenURL:[NSURL URLWithString:@"Twitter://"]]) {    // 推特}